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THE IDENTIFICATION
OF ORGANIC • X ,
COMPOUNDS -

By
G. B. NEAVE, M.A., D.Sc. (St. Andrews)

and
I. M. HEILBRON, Ph.D. (Leipzig), F.I.C.

LECTURERS AND DEMONSTRATORS, DEPARTMENT

OF CHEMISTRY, GLASGOW AND WEST OF

SCOTLAND TECHNICAL COLLEGE

CONSTABLE & CO., LIMITED
1911

BUTLER & TANNER

THE SELWOOD PRINTING WORKS

FROME AND LONDON

Preface

IN teaching practical organic chemistry we have
found the want of a convenient text-book dealing
with the identification of simple organic compounds,
such as is required by students working for the Inter-
mediate and Final (Branch d) Examinations of the
Institute of Chemistry. Moreover, many of the
reactions and physical constants are not easily acces-
sible, but are only to be obtained by a diligent and
often tedious search through some of the larger books
of reference.

In this small volume we have endeavoured to
bring together in a convenient form the principal
reactions and physical constants of the most import-
ant organic substances. Our aim has been to elimin-
ate, as far as possible, guess-work on the part of the
student, and to provide him with methods by which
he can readily detect the more important groups in
the compound, assign it to its class, and then com-
plete its identification by referring to the section
dealing with the class to which it belongs. Wherever

288249

iv PREFACE

possible, an easily prepared derivative is described
under each compound.

In many cases descriptions of operations are brief,
as we assume that the student has already attended
lectures on Organic Chemistry and worked through
a satisfactory course of Preparations.

The scheme adopted in this book having given
satisfactory results in the laboratories of this College,
we now venture to give it wider publicity.

We are deeply indebted to Professor G. G. Hen-
derson for the interest he has taken in the work, and
for a number of valuable suggestions.

G. B. N.

I. M. H.

GLASGOW,

April, 1911.

Contents

SECTION PAGE

I PRELIMINARY TESTS .... 1

II TESTS FOR THE ELEMENTS ... 4

III GROUP REACTIONS .... 8

IV HYDROCARBONS 14

V ALCOHOLS ...... 19

VI ETHERS 22

VII PHENOLS 23

VIII ALDEHYDES .29

IX KETONES 36

X ACIDS . 38

XI AROMATIC SULPHONIC ACIDS ... 48

XII ACID ANHYDRIDES . . . .52

XIII ACID HALIDES 53

XIV ACID AMIDES 53

XV ACID IMIDES 55

XVI ACID ANILIDES . . . . .55

XVII ESTERS. 56

vii

viii CONTENTS

SECTION PAGE

XVIII QUINONES 58

XIX CARBOHYDRATES ..... 60

XX GLTJCOSIDES . . . . . .61

XXI AMINES 62

XXII NITRO COMPOUNDS .... 68

XXIII NITROSO COMPOUNDS .... 72

XXIV NlTRILES AND ISONITRILES . . . 74
XXV ISOCYANATES. . . . . .75

XXVI UREAS AND UREIDES . . . .75

XXVII URIC ACID GROUP .... 78

XXVIII HALOGEN COMPOUNDS . . . .80

XXIX Azo COMPOUNDS . . . . .83

XXX PYRIDINE AND QUINOLINE GROUP . . 85

XXXI ALKALOIDS . . . . . .86

XXXII SULPHUR COMPOUNDS . . . .89

XXXIII TERPENES AND ALLIED COMPOUNDS . 94

XXXIV ALBUMINS AND PROTEIDS . . .97
APPENDIX ... . . .99

INDEX . 101

I. PRELIMINARY TESTS.

1. ORGANIC compounds are often characterized
by their appearance and smell, and the experienced
student may frequently be able to classify and in
some cases to identify a substance by means of these
physical properties.

Colour is generally induced in a compound by the
presence of the following common groups : —

(a) Nitro group. The compound is then gener-
ally yellow.

(6) Nitroso group. The compound in the fused
state or in solution (if monomolecular) is blue to
green in colour.

(d) Compounds having a quinonoid structure are
usually strongly coloured. The common quinones
are all deep yellow.

2. If the substance is a solid, a small quantity is
heated on platinum foil and the changes which occur
are carefully noted.

(a) A sooty flame indicates a high percentage of
carbon in the substance. The compound is then
probably one of the aromatic series.

•

2.: ... THE IDENTIFICATION OF

, t(6J An ihcpmbu'stible residue indicates the pres-
ence .bt ''a* m&tai *r*r some inorganic matter in the
compound, which is then tested for in the usual
manner.

It must be remembered, however, that the metals
Mercury and Arsenic, likewise Ammonium salts, are
volatile.

3. The solubility of the substance in water is
tested.

(a) With the exception of certain salts, substances
containing hydroxyl radicles usually dissolve.

(6) The following classes of compounds are also
generally soluble : — Lower alcohols, aldehydes,
ketones, monobasic acids, polybasic acids, substi-
tuted acids, carbohydrates (except starch and
cellulose), lower amines and amides, urea and its
homologues, thioureas, cyanates, alkyl sulphates.

(i) An acid reaction indicates the presence of a
carboxyl or sulphonic group in the substance. A
salt of a weak base would be hydrolytically dissoci-
ated in dilute solution with a resulting acid reaction.

Acid chlorides are rapidly, acid anhydrides slowly,
decomposed by water, especially on warming.

(ii) An alkaline reaction usually indicates the
presence of a free base.

4. A small quantity of the substance (about
0-25 gram) is heated with a large excess of soda-lime
in a hard glass test-tube fitted with a cork and a,
short right-angled delivery tube,

ORGANIC COMPOUNDS 3

(a) Many nitrogen compounds evolve ammonia.
An amine is liberated from an amine salt.

(6) Formates are decomposed with evolution of
hydrogen.

(d) Phenols are formed from hydroxy aromatic
acids or their salts.

(e) A smell of burnt sugar is observed from carbo-
hydrates, 'glucosides and many higher acids such as
citric acid, tartaric acid, malic acid, tannic acid
and gallic acid.

5. The substance is warmed with concentrated
caustic soda solution. NSV^^

(a) Ammonia is evolved from ammonium salts?
amides, and imides.

(6) Amines are liberated from their salts. The
lower aliphatic amines have characteristic ammonia -
cal fishy odours and are inflammable. The aromatic
amines are insoluble oils or solids.

(c) Acetyl derivatives of amines are decomposed,
liberating the free amine. The decomposition is
only accomplished by prolonged heating.

(d) Esters are slowly hydrolysed with liberation
of the alcohol. The vapours of the lower alcohols
are inflammable. The pleasant characteristic odour
of the ester disappears.

(e) Acids, phenols and nitrophenols dissolve with
formation of a salt. The nitrophenols give red or
yellow solutions.

(/) Alkaloids are precipitated from solutions of

4 THE IDENTIFICATION OF

their salts. Morphine is only slowly precipitated
from a solution of its salt and is readily soluble in
excess of the reagent.

(g) Aliphatic aldehydes, with the exception of
formaldehyde, are converted into resins.

(h) Solutions of glucose and lactose are turned
brown.

6. Dilute sodium carbonate solution is added to
a small quantity of the substance contained in a
test-tube, and the mixture is gently warmed.
Acids, chlorophenols, nitrophenols and polyhydric
phenols readily dissolve. Monohydric phenols are
insoluble.

7. In order to ascertain if the substance is a
saturated or unsaturated compound, a small quan-
tity is dissolved in chloroform or in some suit-
able solvent having no action on bromine and a
dilute solution of bromine in the same solvent is
added, drop by drop. If the bromine is instantly
decolourized without a simultaneous evolution of
hydrobromic acid, the presence of a double or treble
bond is shown, the substance being unsaturated.

II. TESTS FOR THE ELEMENTS.

Oxygen cannot be detected by any direct test, and
the indications of its presence in a substance must
be inferred from the foregoing experiments.

ORGANIC COMPOUNDS 5

It is not generally necessary to make any special
tests for Carbon and Hydrogen.

The presence of Nitrogen in an organic substance
is indicated by heating a small quantity of the com-
pound in a hard glass test-tube with excess of soda-
lime. If ammonia is evolved, the presence of
nitrogen is proved.

As, however, nitro-compounds, azo-compounds
and some other nitrogen compounds do not respond
to this test, the following delicate test must be applied
before the absence of nitrogen may be considered
conclusively proved.

A small piece of sodium, about the size of a pea,
is dropped into a dry hard glass test-tube and gently
warmed till it melts, after which a little of the sub-
stance, about 0-1 gram, is introduced in such a
manner that it falls directly on the sodium. If the
substance is a liquid it is allowed to fall drop by
drop on the sodium, care being taken to prevent
it touching the sides of the tube. After the first
violent action has ceased, the tube is heated in a
Bunsen flame till all apparent change is over.

The tube is allowed to cool and 10 cc. water are
carefully added. The mixture is boiled for a few
minutes and, if necessary, filtered from any carbon-
aceous matter.

If the filtrate be divided into three portions the
presence of a halogen or of sulphur in the substance
may also be directly tested.

One portion of the original solution or filtrate is
now treated with a few drops of caustic soda solu-

6 THE IDENTIFICATION OF

tion, a little freshly-prepared ferrous sulphate solu-
tion and finally a few drops of ferric chloride solu-
tion, and the whole well shaken. On carefully
acidifying with concentrated hydrochloric acid a
blue solution or precipitate of Prussian blue is
formed, proving the presence of nitrogen in the
original substance.

Note. — With substances containing only a small
percentage of nitrogen a greenish-blue solution is
frequently obtained which may only show the
Prussian blue precipitate after standing for a con-
siderable time.

The formation of the Prussian blue depends on the
fact that the nitrogen and carbon combine with the
sodium to yield sodium cyanide. This compound in
presence of ferrous hydroxide combines to give
sodium ferrocyanide —

Fe(OH)2 + GNaCN =Na4FeC6N6 +2NaOH

After the addition of ferric chloride and acid the
insoluble Prussian blue is precipitated —

3Na4FeC6N6 + 4FeCl3 =Fe4(FeC6N6)3 + 12NaCl.
After testing the one portion for the presence of
nitrogen another portion is acidified with nitric acid,
the solution boiled to expel any hydrocyanic acid
present, and then silver nitrate solution is added.
If a precipitate is formed the presence of a halogen
in the original substance is indicated and its nature
may be determined by submitting the precipitate
to the usual examination for the detection of cMorine,
bromine, or iodine. This test depends on the

ORGANIC COMPOUNDS 7

formation of sodium halide produced by combination
of any halogen in the original substance with the
metallic sodium.

Another simple test to prove the presence of
a halogen in a substance is obtained by wrapping
a small piece of copper oxide within a stout
copper wire, heating it in a Bunsen flame until
no green colouration is produced, and allowing it
to cool. A very small quantity of the substance
is then placed on the oxide, which is again heated
in the flame, when, if a halogen be present, a green
colouration is observed, due to the formation of a
volatile halogen compound of copper. This test
is not absolutely conclusive, as some non-halogen-
compounds appear able to produce a similar coloura-
tion. Further, by this test, no information is
obtained as to which halogen is present.

Sulphur in a compound is best detected by taking
the third portion from the sodium extract as already
described, and placing a drop of the alkaline solution
on a silver coin. If the original substance contained
sulphur, sodium sulphide will have been produced,
forming on the silver coin a black precipitate of
silver sulphide.

The presence of sodium sulphide in the alkaline
filtrate is also readily detected by the addition of
sodium nitroprusside solution, which produces a
deep violet colouration with an alkali sulphide.

Phosphorus may be detected by fusing a small
quantity of the substance with a mixture of equal
portions of potassium nitrate and carbonate on a

8 THE IDENTIFICATION OF

piece of platinum foil. The residue is dissolved in
water, acidified with a few drops of concentrated
nitric acid and a phosphate tested for in the usual
way with ammonium molybdate.

III. GROUP REACTIONS.

FROM the foregoing preliminary tests the student
will have deduced the type of compound with which
he is dealing, or at any rate something of its nature.
The following tests for individual groups may now
be performed : —

, HYDROXYL GROUP.

(a) A small quantity of the compound is heated
for about fifteen minutes with an excess of acetic
anhydride.

If a hydroxyl group is present an acetyl derivative
(oily or crystalline) is thus formed which may
then be separated, washed with dilute sodium car-
bonate solution and finally hydrolysed by heating
under a reflux condenser with caustic soda solution.
The acetyl compound is, in this way, decomposed
with formation of an acetate which can readily be
recognized by applying the usual tests for acetic
acid or acetates (see page 38).

(b) SCHOTTEN-BAUMANN REACTION. — About 1

ORGANIC COMPOUNDS 9

gram of the compound is vigorously shaken up
with about 1 cc. benzoyl chloride and sufficient
dilute caustic soda solution to render the mixture
alkaline. The product is poured into water and
the crystalline benzoate separated by filtration,
washed with water and then hydrolysed with caustic
soda solution. After hydrolysis an alkali benzoate
is formed, which can be detected in the usual manner
(see page 41).

If required, the benzoyl derivative may be puri-
fied by recrystallization from alcohol, and its
melting point determined.

METHOXY AND ETHOXY GROUPS.

Seven cc. hydriodic acid (Sp. Gr. 1-7) are added
to about 0 -2 gram of the compound in a test-tube
fitted with cork and delivery tube, the end of which
dips into an alcoholic solution of silver nitrate.
The mixture is very gently heated in a glycerine
bath to 140° and, if a methoxy or ethoxy group be
present, methyl or ethyl iodide distils over and
produces a precipitate of silver iodide in the alcoholic
silver nitrate solution.

ALDEHYDE GROUP.

(a) TOLLEN'S REACTION. — Ammonium hydroxide
solution is cautiously added to about 2 cc. silver
nitrate solution until the precipitate which is first
formed is just redissolved. One cc. caustic soda
solution is next run in and then 2 or 3 drops of

10 THE IDENTIFICATION OF

the supposed aldehyde solution. If an aldehyde
group is present an immediate deposit of metallic
silver is produced in the cold.

(6) SCHIFF'S REACTION. — A few drops of the
aldehyde are poured into about 5 cc. of a solution
of Schiff 's reagent (magenta solution which has been
decolourized by sulphur dioxide). The red coloura-
tion of the magenta is immediately restored.

It should be noted that some ketones if present
in large quantity react similarly, although the
reappearance of the colour is more gradual and
shows first after the mixture has stood for some
time.

(c) Fehling's solution is rapidly decomposed
with precipitation of red cuprous oxide on being
warmed with an aliphatic aldehyde.

Aromatic aldehydes do not give this reaction.

(d) If about 1 cc. of an aliphatic aldehyde is
warmed with 2 cc. concentrated caustic potash
solution, a brown precipitate of aldehyde resin
separates out.

Formaldehyde and aromatic aldehydes do not
react in this manner, but yield mixtures of alcohols
and acids, both containing the same number of
carbon atoms as the original aldehyde.

2R-CHO +KOH = R-CH2OH +R-COOK.

(e) If 1 cc. of an aldehyde is vigorously shaken up
in a test-tube with a few cc. of a cold saturated solu-
tion of sodium hydrogen sulpnite l a precipitate

1 See Appendix, page 100.

ORGANIC COMPOUNDS 11

of the aldehyde " bisulphite compound " is formed.
Sodium carbonate solution liberates the aldehyde
from the acid sulphite compound.

Some ketones produce similar crystalline com-
pounds.

KETONE GROUP.

If an aldehyde group is absent the presence of a
ketone group may be confirmed by the preparation
of the semicarbazone of the ketone (see page
30 for this preparation).

AMINO GROUP.

(a) CARBYLAMINE TEST : — About 0-1 gram of the
substance is mixed with 3 drops of chloroform and
2 cc. alcoholic potash, and the whole carefully
warmed. The characteristic disgusting carbyl-
amine odour is produced if the substance contains
an amino group.

(6) A small quantity of the compound is dissolved
in a few cc. hydrochloric acid and sodium nitrite
solution is then added until an excess of free nitrous
acid is present. On warming, the amino group is
converted into hydroxyl, with a vigorous evolution
of nitrogen.

Aliphatic amines and aromatic amines having the
amino group in a side chain produce alcohols.

Aromatic primary amines with the amino group
in the. nucleus form phenols.

12 THE IDENTIFICATION OF

To distinguish between the two classes of aro-
matic amines, the amine is diazotized (see page 64)
in the cold, and a solution of /3-napthol in caustic
soda added. An intensely coloured azo dye is
produced if the amino group is in the nucleus.

IMINO GROUP.

If sodium nitrite is added to an acid solution
of the compound, a yellow precipitate or solution
of a nitrosoamine is formed, which may be con-
firmed by applying LIEBERMANN'S TEST for nitro-
soamines : —

The precipitate or solution containing the nitroso-
amine is extracted with ether, the ethereal solution
washed and dried rapidly over calcium chloride
and the ether then blown off. To the residue, oil
or solid, is now added a small quantity of phenol
and 4 to 5 drops concentrated sulphuric acid, when
a deep greenish black colouration is produced. On
pouring the mixture into water a red solution is
formed, which is changed to blue or green on addition
of alkalies.

Note. — With aliphatic tertiary amines no reaction
results on addition of nitrous acid, but dialkylani-
lines interact readily, intensely coloured green
nitroso compounds being formed, the NO-group
displacing hydrogen of the benzene nucleus from
the para position to the nitrogen atom. Substances
of this type do not give Liebermann's reaction.

The hydrochlorides of these para-nitroso bodies,

ORGANIC COMPOUNDS 13

which would be precipitated on addition of sodium
nitrite to a hydrochloric acid solution of a dialkylani-
line, are generally yellow in colour and must not
be confounded with the secondary nitrosoamines.

NITRO GROUP.

A small quantity of the substance is mixed in a
test-tube with about 2 cc. concentrated hydro-
chloric acid and to this 1 gram zinc dust is gradually
added in small quantities, and the mixture finally
warmed. About 5 cc. water are now run in and
then concentrated caustic alkali until the precipitate
at first formed is redissolved. The amine produced
is extracted with ether, and the presence of the
amino group can be recognized by the tests given
in the preceding paragraph.

NITRILES AND ISONITRILES.

(a) A small quantity of the substance is heated
with 20 cc. concentrated hydrochloric acid under
a reflux condenser. The reaction mixture is then
made alkaline with caustic soda and heated.

Ammonia is evolved from nitriles, whereas the
isonitriles yield under the same conditions sodium
formate and an amine.

(6) MENDIUS' REACTION FORNrrniLES.1 — Nitriles,
when reduced in a similar manner to that described
for the reduction of nitro-compounds, yield amines
which can readily be isolated and identified.
1 See page 74,

14 THE IDENTIFICATION OF

AZO-GROUP.

Azo dye-stuffs when vigorously reduced, yield
amines, either simple or complex. About 1 gram
of. the substance is treated with about 20 cc. of a
concentrated solution of stannous chloride in hydro-
chloric acid. Caustic soda solution is then added
until the precipitate first formed is just redis-
solved. Free amines are liberated which may
be separated, and the usual tests for the amino
group applied.

IV. HYDROCARBONS.

THESE are generally colourless liquids or solids,
practically insoluble in water, soluble in alcohol
and ether. The solubility in the last mentioned
solvents decreases with increase in the molecular
weight of the compound.

ALIPHATIC HYDROCARBONS.

%-Pentane, C5H12, is an exceptionally stable
colourless liquid, boiling at 36-37°.
?&-Hexane, C6H14, boils at 69-70°.
n-Heptane, C7H16, boils at 97-98°.
^-Octane, C8H18, boils at 124°.

Isoprene, ^TT2>C-CH=iCH2, is a colourless liquid

ORGANIC COMPOUNDS 15

boiling at 37°, obtained by dry distillation of
caoutchouc. Concentrated hydrochloric acid con-
verts isoprene into a substance very similar to, if
not identical with, caoutchouc.

AROMATIC HYDROCARBONS.

Benzene, C6H6, B.P. 80-81°, M.P. 54°. The
pure hydrocarbon has a peculiar, not unpleasant
smell. It is exceedingly stable towards oxidizing
agents.

If 1 gram of the hydrocarbon be added to a mix-
ture of 3 grams concentrated sulphuric acid and
2 grams concentrated nitric acid (Sp. Gr. 1-4), and
the mixture warmed on a water-bath for about
J hour at 60°, nitro-benzene is obtained, and on
cooling may be separated from the lower layer of
acids, washed, dried and identified [(see page 70)

C6H6 +N02-OH = C6H5N02 +H20.

Toluene, C6H5-CH3,B.P. 110°. Toluene on treat-
ment with chromic acid yields benzoic acid.

About 1 gram of the substance is heated under
a reflux condenser with a mixture consisting of 2
parts potassium dichromate, 3 parts concentrated
sulphuric acid and 3 of water. After oxidation
the solution is filtered while hot, when on cool-
ing benzoic acid separates out and may be tested
for as shown on page 41.

o-Xylene, CJBT4 boils at 142°. With dilute

potassium permanganate it yields phthalic acid.

16 THE IDENTIFICATION OF

A small quantity of the hydrocarbon is heated
under a reflux condenser for some time with dilute
alkaline potassium permanganate. The solution
is then, if necessary, treated with sulphurous acid
to remove excess of potassium permanganate,
filtered off from the separated manganese dioxide
and acidified. The acid is then extracted with
ether, dried with calcium chloride and the tests for
phthalic acid applied (see page 42).

m-Xylene and p-Xylene, boiling points 139° and
138° respectively, are distinguished from each other
by the fact that the meta-compound is sulphonated
in the cold with sulphuric acid, while the para-
compound remains unchanged.

Ethylbenzene, C6H5 -Calls, boils at 134°. Chromic
acid oxidizes it to benzoic acid.

Mesitylene, CeHgfCHs^l : 3 : 5, is an agreeably
smelling liquid boiling at 163-164°. With chromic
acid mesitylene is decomposed into acetic acid.

Cumene, C6H5 •CH(CH3)2, is a colourless liquid
boiling at 152-153°. On oxidation with chromic
acid or dilute nitric acid it is converted into benzoic
acid.

Cymene, C6H4<niJ;LTj |.|, is a pleasant smell-

^•UhL(Ubi3)2(4)

ing liquid boiling at 175°.

Diphenyl, C6H5 -Cells, is a colourless, crystalline
solid, melting at 71°, B.P. 254° ; when oxidized
with chromic acid it is converted into benzoic acid.

Diphenylmethane, C6H5*CH2 -Cells, is a crystalline
solid, M.P. 26 '5°, On oxidation with chromic acid

ORGANIC COMPOUNDS 17

it is converted into benzophenone which may be
extracted with ether and identified (page 37).

Stilbene,C6H5'CH : CH'C6H5j crystallizes in colour-
less needles, M.P. 124-125°. It is unsaturated and
readily adds on two atoms of bromine forming
stilbene dibromide, C6H5-CHBr-CHBr.C6H5, M.P.
137°. Oxidation with chromic acid or alkaline
permanganate yields benzoic acid.

Styrene, C6H5'CH : CH2, is a colourless liquid
which boils at 145°. It is oxidized to benzoic
acid with chromic acid mixture.

Phenylacetylene, C6H5'C = CH, is a colourless liquid
boiling at 139-140°. It yields a yellow copper
compound when mixed with ammoniacal cuprous
chloride solution. On oxidation with chromic
acid, benzoic acid is obtained.

Naphthalene, Ci0H8, crystallizes in lustrous leaflets
which melt at 80° and boil at 218°. It has a char-
acteristic smell, and is very volatile. On addition
of a solution of the hydrocarbon in benzene to a
solution of picric acid in the same solvent, a yel-
low crystalline compound, naphthalene picrate,
CioH8,C6H2(N02)3OH melting at 149° separates
out on standing. Naphthalene on boiling with
dilute nitric acid is oxidized, yielding phthalic acid
and carbon dioxide.

Anthracene, Ci4H10, crystallizes in almost colour-
less lustrous plates, possessing a beautiful violet
fluorescence. It melts at 213°, boils at 360°. With
picric acid it forms the molecular compound
C14H10,C6H2(N02)3OH which is deposited from

18 THE IDENTIFICATION OF

benzene solution in ruby-red needles melting at
138°.

Anthracene is readily oxidized to anthraquinone
by dissolving the hydrocarbon in warm glacial acetic
acid and adding to the solution about double the
weight of chromic anhydride, and then boiling for a
short time. The mixture is largely diluted with
water, the anthraquinone filtered off, washed with
dilute sulphuric acid, then with water and finally
dried. M.P. 273°.

Phenanthrene, Ci4H10, forms colourless leaflets
melting at 99°. It is readily soluble in alcohol,
while the isomeric anthracene is only sparingly
soluble.

It combines with picric acid to give a yellow
compound, phenanthrene picrate, melting at 144°.
With chromic anhydride it yields phenanthra-
quinone, M.P. 205°.

C6H4V

Fluorene | yCH2, crystallizes in colourless
C6H4/

leaflets with a violet fluorescence. It melts at 113°.
The picrate obtained by mixing benzene solutions
of fluorene and picric acid melts at 79-80°.

ORGANIC COMPOUNDS 19

V. ALCOHOLS.

THE common monohydric alcohols are, as a rule,
colourless liquids (diphenyl and triphenyl carbinols
are solids) with a neutral reaction and possessing a
characteristic smell and taste. The lower members
are soluble in water, but the solubility rapidly de-
creases with increase of molecular weight. The
Sp. Gr. is always less than that of water.

The polyhydric alcohols are oily liquids or crystal-
line solids, all readily soluble in water, sparingly
soluble or insoluble in ether.

PRIMARY MONOHYDRIC ALCOHOLS.

Methyl alcohol, CH3OH, is a colourless, mobile
liquid boiling at 66 '5°. It burns with a bluish non-
luminous flame. If a mixture of methyl alcohol
with dilute sulphuric acid and potassium dichromate
be distilled, the distillate contains formic acid
which may be identified (page 38).

When methyl alcohol is heated with salicylic
acid and concentrated sulphuric acid, methyl
salicylate is formed and can be identified by its
odour. On warming methyl alcohol with para-
nitrobenzoyl chloride, the methyl ester is formed,
melting at 96°.

Ethyl Alcohol, C2H5OH, boils at 78°.

1 . When ethyl alcohol is mixed with a little dilute
sulphuric acid and potassium dichromate and the
mixture warmed, the alcohol is oxidized to acetalde-

20 THE IDENTIFICATION OF

hyde which can be recognized by its peculiar choking
smell.

2. The formation of lodoform serves as a delicate
test for ethyl alcohol.1 To a solution of alcohol a
little sodium carbonate is added and the mixture
warmed to about 60°. To this is now added drop
by drop, a strong solution of iodine in potassium
iodide until, after shaking, the liquid remains faintly
brown. lodoform separates out, having a char-
acteristic odour and melting at 119°.

3. The para-nitrobenzoic-ester,

C2H5OOC-C6H4-N02,

is readily obtained as a crystalline solid melting
at 57°.

Propyl alcohol, C3H7OH, boils at 97-4°. It is
miscible in all proportions with water, but on addi-
tion of calcium chloride and other easily soluble
salts it separates out from its aqueous solution,

Normal Butyl Alcohol, C4H4OH, is a liquid with an
agreeable odour boiling at 117°.

Isobutyl Alcohol, ™3>CH-CH2OH, is a liquid

possessing a fusel-oil odour. B.P. 108°.

Normal Amyl Alcohol, C5HuOH, is a liquid almost
insoluble in water, boiling at 137°.

Allyl Alcohol, C3H5OH (CH2 : CH-CH2OH), is a
mobile liquid with a pungent odour, boiling at
96-5°. It has the properties not only of a primary
alcohol, but also of an unsaturated compound.
1 Acetone also gives the lodoform test.

ORGANIC COMPOUNDS 21

On distilling allyl alcohol with chromic acid,
formic acid (page 38) distils over.

Benzyl Alcohol, C6H5'CH2OH, is a colourless liquid,
with a faint aromatic odour and boils at 206°. It
is sparingly soluble in water, readily in alcohol and
ether. On oxidation with dilute nitric acid it
yields first benzaldehyde and then benzoic acid.

SECONDARY MONOHYDRIC ALCOHOLS.

Isopropyl Alcohol (CH3-CHOH-CH3), boils at 82-
83°. Oxidizing agents convert it into acetone.

Diphenyl Carbinol, benzhydrol, (C6H5)2CHOH,
crystallizes in silky needles, very sparingly soluble
in water, M.P. 67-68°. The acetate melts at 41-42°.

TERTIARY MONOHYDRIC ALCOHOLS.

Tertiary Butyl Alcohol, (CH3)3COH, is a colourless
solid melting at 25°, boiling at 83-84°.

Triphenyl Carbinol, (C6H5)3COH, M.P. 159°. The
acetate melts at 99°.

POLYHYDRIC ALCOHOLS.

Ethylene Glycol, CH2OH-CH2OH, is a thick
colourless liquid boiling at 197-198°. When
glycol is heated with solid caustic potash to
250°, hydrogen is evolved and potassium tfxalate
formed which may be identified (see page 39).

Glycerol, C3H5(OH)3, is a colourless, syrupy
liquid with a sweet taste, insoluble in ether.

When glycerol is heated with potassium hydrogen

22 THE IDENTIFICATION OF

sulphate, or with phosphoric anhydride, acrolein
is produced and may be identified by its pungent
disagreeable odour.

When a borax bead is moistened with glycerol
and held near the outer edge of a Bunsen flame
it gives a green colouration.

The following are crystalline solids : —

Erythritol, C4H6(OH)4, M.P. 112°.

Oxidation with cone, nitric acid converts ery-
thritol into oxalic acid. The tetra-benzoate melts
at 186-187°.

Arabitol, CH2OH(CHOH)3CH2OH, M.P. 102°.

Mannitol, CH2OH(CHOH)4CH2OH, M.P. 166°.
The hexabenzoate melts at 124-125°, the hexacetate
at 119°.

VI. ETHERS.

THESE are neutral, volatile liquids, practically
insoluble in water and chemically very indifferent.
They can be best identified by their boiling points.

Ethyl Ether, (C2H5)20, B.P. 34-35°.

Normal Propyl Ether, (C3H7)20, B.P. 90-91°.

Anisol, C6H5'0'CH3 is an ethereal smelling liquid
boiling at 154-155°. Heated with concentrated
hydriodic acid to 140° it decomposes into phenol
and methyl iodide.

Phenetol, CeH6-0-C2H5, boils at 172°.

ORGANIC COMPOUNDS 23

Phenyl Ether, C6H5'0 'Celts, crystallizes in long
needles and possesses a smell resembling geraniums.
It melts at 28°, boils at 252°. It is not reduced on
heating with hydriodic acid.

VII. PHENOLS.

THE phenols, with the exception of m-cresol are
crystalline solids. They are of an acid nature,
the hydrogen of the hydroxyl being readily sub-
stituted by metals. The monohydric phenols are
but sparingly soluble in water, the polyhydric
phenols readily soluble.

Phenol, CeHsOH, is a colourless crystalline solid,
which gradually acquires a reddish colour, and
deliquesces on exposure to air. It melts at 43°,
boils at 181°; it dissolves in 15 parts water and gives
a violet colouration in neutral solution with ferric
chloride.

When an aqueous solution of phenol is mixed
with one -fourth of its volume of ammonia solution
and then with a few drops of a bleaching powder
solution, and gently warmed, a fine blue colour is
produced, which soon disappears.

Bromine water precipitates tribromophenol from
solutions as an oil which soon crystallizes and melts
.at 92°. The crude tribromophenol may if necessary
be purified by recrystallizing from alcohol. The
benzoate melts at 69°.

24 THE IDENTIFICATION OF

o-Cresol, C6H,<3 M.P. 31°. On fusion

with potassium hydroxide, salicylic acid is formed.
With picric acid, a picrate, 2C7H80,3C6H3N307,
melting at 88° is obtained in orange yellow needles.

ra-Cresol is liquid and boils at 202-203°. Ferric
chloride colours an aqueous solution of m-cresol
deep blue violet. The benzoate melts at 54°.

p-Cresol melts at 36° and gives with ferric chloride
a blue colouration. The benzoate melts at 71-72°.

Carvaerol, | is a thick oil boiling at 236-

237°. An alcoholic solution of carvacrol is coloured
green on addition of ferric chloride.

CH3

Thymol, melts at 50-51°, and possesses

k^OH
C3H7

a pleasant aromatic odour. An aqueous solution
of thymol treated with one half its volume of
glacial acetic acid and one volume of concentrated
sulphuric acid produces on warming a red violet
colouration.

a-Naphthol, Ci.0H7OH, melts at 94°, is practically
insoluble in cold water, readily soluble in alcohol
and ether. Bleaching powder solution produces
a dark violet colouration. A naphthol picrate is

ORGANIC COMPOUNDS 25

produced, by mixing alcoholic solutions of the com-
ponents, in orange needles melting at 189°.

a-Naphthol acetate melts at 46°.

PREPARATION OP ACETATE. — One gram of the
naphthol is boiled for about fifteen minutes with
2 grams acetic anhydride. On pouring the product
into water the crude acetate separates out. It is
purified by recrystallization from a small quantity
of water.

a-Naphthol benzoate melts at 56°.

/3-Naphthol melts at 122°. With ferric chloride
a greenish colouration is produced in an aqueous
solution of the naphthol, from which after some time
a white flocculent precipitate is thrown down.
/3-Naphthol dissolved in strong potassium hydroxide
solution and treated with chloroform produces on
warming to 50° a blue colouration which gradually
becomes green and finally brown. /3-Naphthol
acetate, C10H7OOC • CH3, melts at 70°. The ben-
zoate melts at 107°.

Catechol (pyrocatechin), ^H^ melts at

104°. It reduces Fehling's solution on warming.
With lead acetate a white precipitate is obtained.
Ferric chloride produces in an aqueous solution of
catechol an emerald-green colouration, which on
addition of sodium bicarbonate becomes violet-red.

Guaiacol, C6H4<^H3 ^ melts at 31°. Ferric

chloride gives its alcoholic solution an emerald-green
colour.

26 THE IDENTIFICATION OF

Resorcinol, C6H4 , M.P. 118°. Ferric

chloride produces a dark violet colouration. If
equal weights of resorcinol and phthalic anhydride
are gently heated together in a test-tube a yellow
melt is obtained, which, when dissolved in dilute
caustic soda solution, produces a solution showing a
fine green fluorescence (formation of fluorescein).
Bromine water precipitates tribromoresorcinol,
M.P. 111°, from an aqueous solution of resorcinol.
The dibenzoate melts at 117°.

Quinol (hydroquinone), C6H4<^ j: |*|, melts at

169° and is readily soluble in water, alcohol and ether.

With ferric chloride quinhydrone is readily ob-
tained in beautiful metallic green crystals by adding
ferric chloride to a concentrated solution of hydro-
quinone in water. The solution becomes at first
red and then rapidly darkens.

The diacetate and the dibenzoate melt respec-
tively at 123° and 199°.
,CH3 (1)

Orcinol, C6H3/-OH (3), M.P. 107°, is easily soluble

\OH (5)

in water, alcohol and ether. On expo'sure to the air
it becomes red. With ferric chloride a violet-black
colouration is produced. Bleaching powder solu-
tion produces a dark red colouration which soon
changes to yellow. The diacetate melts at 25°,
the dibenzoate at 88°.

Pyrogallol, C6H3(OH)3 1:2:3, melts at 132-133°

ORGANIC COMPOUNDS 27

and is readily soluble in water, alcohol and ether.
An alkaline solution of pyrogallol quickly absorbs
oxygen from the air and becomes brown. An
aqueous solution of pyrogallol is turned brown on
addition of nitrous acid solution. The tribenzoate
melts at 90°.

Phloroglueinol, C6H3(OH)3 1:3:5, melts at 218°
on quickly heating. It is readily soluble in water,
alcohol and ether. With ferric chloride a blue-
violet colouration is obtained. The acetate melts
at 105°, the benzoate at 173°. The trioxime melts
at 43°.

ALCOHOL PHENOLS.

Saligenin, C ' M'R 86°> is

readily soluble in boiling water, alcohol and ether.
It dissolves in concentrated sulphuric acid with an
intense red colour. With ferric chloride it gives
a blue colouration.

Anisyl Alcohol, CeH^* , melts at 45°.

Dilute nitric acid oxidizes it to anisic acid, M.P.

185°.

HALOGEN PHENOLS.

o-Chlorophenol, C6H4<^,, , has an unpleasant

odour and boils at 175-176°.

m-Chlorophenol is obtained as crystals melting at

28-5°.

28 THE IDENTIFICATION OF

2>-Chlorophenol melts at 37°. It possesses a faint,
unpleasant odour. Fused with alkalies it gives
resorcinol.

o-Bromophenol is an unpleasant-smelling oil, boiling
at 194-195°.

m-Bromophenol melts at 32-33°.

p-Bromophenol melts at 63-64°.

o-Iodophenol is obtained as needles, melting at 43°.
It is fairly soluble in hot water, readily soluble in
alcohol and ether. By warming with nitric acid
(Sp. Gr = 1«2) picric acid is formed.

m-Iodophenol melts at 40°.

2>-Iodophenol forms long needles melting at 92°.
By boiling with nitric acid it is readily converted
into picric acid.

Trichlorophenol, melts at 67-68° and

has an acid reaction. With hydrochloric acid and
potassium chlorate, chloranil (see page 59) is formed.
Tribromophenol (2:4:6) melts at 95°. The acetate
recrystallized from alcohol melts at 82°.

AMINOPHENOLS

-VTTT

o-Aminophenol, C6H4<^: 2, when pure is colour-

less, but readily becomes brown. It melts at 170°,
and is somewhat sparingly soluble in water, Teadily
in ether. The acetate melts at 150°.

ORGANIC COMPOUNDS 29

p-Aminophenol melts with" decomposition at 184°.
With chromic acid it is readily oxidized to quinone.
p-Aminophenol Methyl Ester (pp — . anisidine)

OPTT 1 1 ^

3 )* forms plates melting at 52-56°.

Phenacetin, C6H4<"2nTT . melts at 135°.

On hydrolysis with caustic soda it yields sodium
acetate, and phenetidine, B.P. 244°.

VIII. ALDEHYDES.

THE lower aldehydes are volatile liquids soluble in
water and possessing a characteristic odour. The
higher members of the series are solids, insoluble in
water.

In chemical properties the aldehydes are neutral
substances, easily oxidized to corresponding acids,
their ready oxidation by the salts of the noble metals
being one of the characteristics of the aldehydes.

All aldehydes form oximes with hydroxylamine,
phenylhydrazones with phenylhydrazine and semi-
carbazones with semicarbazide hydrochloride. As
these derivatives can readily be obtained in the pure
state and are generally solids, their preparation and
melting-point determination serve as an aid in the
identification of an aldehyde.

PREPARATION OF AN OXIME. — One gram of the

30 THE IDENTIFICATION OF

aldehyde dissolved in the least possible quantity of
alcohol is treated with a slight excess of hydroxyl-
amine hydrochloride dissolved in a little water.
To this mixture is added the theoretical quantity of
sodium hydroxide in concentrated solution. If any
precipitate is now formed, alcohol or water, as may
be necessary, is added to bring about complete solu-
tion. The solution is then heated on a water-bath
under a reflux condenser for from one to two hours.
The reaction mixture is then poured into water,
made faintly acid with acetic acid and the oxime
extracted with ether, the ethereal solution dried,
the ether distilled off and the oxime recrystallized
from some suitable solvent.

PREPARATION OF A PHENYLHYDRAZONE. — One
cc. phenylhydrazine is added to about 5 cc. water
and sufficient acetic acid added, with vigorous shak-
ing, to bring about complete solution. About 0-5
gram of the aldehyde is now added (in solution if
necessary) and the mixture vigorously shaken and
very gently warmed. The phenylhydrazone separ-
ates out and, if solid, is filtered off, washed with
dilute acetic acid, dried on a porous plate or be-
tween filter paper, and finally recrystallized from
alcohol or benzene.

PREPARATION OF A SEMICARBAZONE. — One gram
of the aldehyde, dissolved in the smallest possible
quantity of alcohol is added to a solution containing
2 grams semicarbazide hydrochloride dissolved in the
minimum quantity of water. A cold alcoholic solu-
tion containing 2 grams potassium acetate, best

ORGANIC COMPOUNDS 31

prepared by boiling the acetate with alcohol, is now
added, and, if any precipitate forms, water or alcohol,
as the case requires, is then carefully added until a
clear solution is obtained. The mixture is then
allowed to stand for some hours, the aldehyde semi-
carbazone gradually separating out.

The addition of a few drops of methyl alcohol (free
from acetone) often accelerates the separation of
the semicarbazone. The semicarbazone obtained is
finally recrystallized from methyl or ethyl alcohol.

Formaldehyde, H-CHO, is gaseous at the ordinary
temperature and is usually met with in solution, the
aqueous solution possessing a penetrating, suffocat-
ing odour. When its aqueous solution is mixed with
ammoniacal silver nitrate solution a silver mirror is
obtained.

Trioxymethylene (H»CHO)3, is a crystalline com-
pound which sublimes readily under 100°. When
strongly heated it is decomposed into pure gaseous
formaldehyde. It is readily soluble in cold sodium
hydroxide solution, insoluble in alcohol and ether.

Aeetaldehyde, CH3-CHO, is obtained as a strongly-
smelling suffocating liquid, boiling at 21° and miscible
in all proportions with water. Boiling with potas-
sium hydroxide solution produces the yellow-brown
aldehyde resin. Aeetaldehyde combines readily
with ammonia gas to give aldehyde ammonia, a
colourless crystalline solid. Its phenylhydrazone
melts at 99°, the semicarbazone at 162°, the oxime
at 47°.

Para-aldehyde (C2H40)3, boils at 124° and on dis-

32 THE IDENTIFICATION OF

tillation is completely converted into acetaldehyde.
It gives none of the usual aldehyde reactions.

Meta-aldehyde (C2H40)3, is isomeric with parajalde-
hyde. It is a crystalline solid which sublimes at
112° without melting. On distillation with dilute
sulphuric acid it breaks down into acetaldehyde.
Like para-aldehyde it gives none of the aldehyde
reactions.

Aldol, CH3-CH(OH)CH2-CHO, is a syrupy liquid
which decomposes at 135° into crotonaldehyde and
water —

CH3CH(OH)CH2-CHO = CH3CH :CH-CHO+H20.
It is soluble in water and alcohol, and gives the
usual aldehyde reactions.

Acrolein, CH2 : CH»CHO, is a pungent-smelling
liquid, boiling at 52-53°. It is readily oxidized to
acrylic acid.

Crotonaldehyde, CH3-CH : CH-CHO, is an ex-
tremely disagreeable-smelling liquid boiling at 104°.
The oxime melts at 119-120°.

Benzaldehyde, C6H5'CHO, is a pleasant aromatic
smelling liquid, which boils at 179°. It does not
reduce Fehling's solution but gives most of the alde-
hyde reactions. Its oxime melts at 35°, the phenyl-
hydrazone at 155°, the semicarbazone at 214°.

o-Toluic Aldehyde, C6H 4<5™ , boils at 200°. Its

oxime melts at 48-49°.

ra-Toluic Aldehyde boils at 199°.

p-Toluie Aldehyde is a liquid with a pepper-like
odour, boiling at 204°. The oxime exists in two

ORGANIC COMPOUNDS 33

forms. The anti-derivative melts at 79°, the syn-
compound at 109°.

CHO

2>-Cumic Aldehyde, Cuminol, | I is a pleasant,

CH(CH3)2

aromatic-smelling liquid, boiling at 237°. Its oxime
melts at 58°.

Cinnamic Aldehyde, C6H5-CH : CH-CHO, decom-
poses on boiling. The phenylhydrazone melts at
168°.

SUBSTITUTED ALDEHYDES.

Chloral, CC13 • CHO, is a colourless, pungent-smell-
ing liquid boiling at 97-98°. Concentrated alkali
solutions decompose chloral even at ordinary temper-
atures into chloroform and alkali formate —

CC13-CHO + KOH = CHC13 + H-COOK.
The oxime melts at 39-40°.

Chloral Hydrate, CC13-CH(OH)2, melts at 57°.
It is readily soluble in water and alcohol. It does
not show the usual aldehyde reactions. By shaking
with concentrated sulphuric acid it is immediately
converted into chloral.

Bromal, CBr 3- CHO, boils at 174°. With alkalies
it is decomposed into brompform and alkali formate.

Bromal Hydrate melts at 53-54°.

Cl
o-Chlorobenzaldehyde, CaH^^^^ , is a liquid, boil-

ing at 213-214°, with a strong odour. Its oxime
melts at 75° (anti), the syn. derivative at 98-102°.

34 THE IDENTIFICATION OF

m-Chlorobenzaldehyde is obtained in long prisms,
melting at 17-18°, boiling at 213°. Oxime, M.P.
70° (syn.).

p-Chlorobenzaldehyde is a solid with an odour like
benzaldehyde, melting at 47-48°.

OTTO
o-Nitrobenzaldehyde, C6H4< , is obtained in

the form of long, pale yellow needles, melting at
44°. It has an odour similar to that of benzalde-
hyde, is readily soluble in alcohol and ether, sparingly
in water. Concentrated aqueous sodium hydroxide
converts it readily into o-nitrobenzoic acid and o-
nitrobenzylalcohol. The oxime melts at 96°.

ra-Nitrobenzaldehyde melts at 58°. It is fairly solu-
ble in hot water, readily in alcohol and ether. The
oxime melts at 118°.

p-Nitrobenzaldehyde melts at 106°. With chromic
acid it is converted into its corresponding acid. The
oxime melts at 129°.

o-Nitrocinnamic aldehyde, C6H4?: CH ' CHO'

melts at 127° and is soluble in hot water.

ra-Nitrocinnamie aldehyde, M.P. 116°.

2>Nitroeinnamic aldehyde melts at 141°. The
oxime melts at 178-179°.

o-Aminobenzaldehyde, ^^< obtained in

silvery leaflets melting at 39-40°, readily soluble
in alcohol and ether, sparingly in water. The
acetyl derivative melts at 70°, the oxime at 132°,

ORGANIC COMPOUNDS 35

ra-Aminobenzaldehyde is a yellow amorphous sub-
stance. The oxime melts at 88°.

p-Aminobenzaldehyde melts at 70-71°. The hydro-
chloride is obtained in red crystals. The acetyl
derivative melts at 155°, the oxime at 124°.

Salicylic Aldehyde, C6H4<^Q |*j, is a pleasant-
smelling oil, boiling at 196°. On oxidation it yields
salicylic acid. The acetyl derivative melts at 37°,
the oxime at 57°.

m-Hydroxybenzaldehyde melts at 104°. The aque-
ous solution is coloured deep violet with ferric
chloride solution. The oxime melts at 87°.

^-Hydroxybenzaldehyde melts at 115-116° and sub-
limes undecomposed. The aqueous solution is
coloured faintly violet with fermp^chloride. The
oxime melts at 65°.

Anisic Aldehyde, C6H4<5?-2 ,(!?, boils at 248°.
^UUfets (4)

The oxime melts at 61°. *

/CHO (1)
Protocatechuie Aldehyde, C6H3^-OH (3), melts at

\OH (4)

153°. Ferric chloride colours an aqueous solution
of protocatechuic aldehyde green ; on addition of
sodium carbonate the colour changes to violet and
then to red. The oxime melts at 150°.

/VCHO (1)

Vanillin, C6H3<J— OCH3 (3) has a pleasant, vanilla-
NOH (4)

like odour and melts at 80-81°. It gives with ferric

36 THE IDENTIFICATION OF

chloride a blue colouration. The benzoate melts at
75°, the oxime at 117°.

Piperonal, C6-.

\^ ^>CH2, has a pleasant helio-

trope odour. It melts at 37°. The oxime melts at
110-112°, the phenylhydrazone at 100°.

Closely related to the aldehydes themselves are
the aldehyde ethers. These are liquids, sparingly
soluble in water, which on boiling with dilute hydro-
chloric acid are readily broken up into their consti-
tuent aldehyde and alcohol.

Methylal CH2(OCH3)2, B.P. 42°.

Acetal, CH3-CH(OC2H5)2, B.P. 104°.

IX. KETONES.

THE aliphatic ketones are liquids, the common aro-
matic ketones are solids. They are only oxidized
with difficulty and therefore do not reduce alkaline
silver solutions. Only those ketones with a methyl
group directly attached to the carbonyl group form
bisulphite compounds. Like aldehydes they form
oximes, phenylhydrazones, and semicarbazones.
The methods for the preparation of these derivatives
are similar to those employed in the case of the
aldehydes.

Acetone, CH3-CO-CH3, B.P. 56°, is miscible with

ORGANIC COMPOUNDS 37

water in all proportions. With iodine and caustic
potash it forms iodoform. The oxime melts at
59-60°.

Methylethylketone, CH3-CO-C2H5, boils at 80-81°.
The oxime is an oil, the semicarbazone melts at
135-136°.

Diethylketone, C2H5-CO-C2H5, B.P. 102-103°.

Dipropylketone, C3H7-CO-C3H7, B.P. 144°.

Pinacoline, CH3C'CO-CH3, is a peppermint-

C
/

smelling liquid boiling at 106°. It forms no bisul-
phite compound. The oxime melts at 74-75°.

Aeetophenone, C6H5-CO-CH3, melts at 20°. With
picric acid it gives a picrate, greenish-yellow crystals
melting at 53°. The oxime melts at 59°.

Benzophenone, C6H5 -CO -Cells, melts at 48-49°.
The oxime melts at 139-140°, the phenyl-hydra-
zone at 137°.

Benzoin, C6H5-CHOH-CO-C6H5, melts at 137°.
It is converted into benzil by means of nitric acid.
Fehling's solution is readily reduced by means of
benzoin. The oxime melts at 151-152° (a-deriva-
tive).

Deoxybenzom, C6H5 -0*3(00 -CeHg, melts at 60°,
The oxime melts at f?> the phenylhydrazone at
116°.

Benzil, C6H5.CO-CO-C6H5, melts at 95°. The
dioxime melts with decomposition at 237°.

38 THE IDENTIFICATION OF

X. ACIDS.

To obtain the acid from a salt, the latter is dissolved
in water (if it is insoluble, it is boiled with sodium
carbonate and filtered), and the solution acidified.
In many cases the acid will be precipitated ; if
soluble in water it is extracted with ether, the
ethereal solution dried and the ether distilled off.
The physical and chemical properties of the acid
are then determined.

1. SATURATED ALIPHATIC MONOBASIC ACIDS.

The lower members are liquids, soluble in water,
the solubility decreasing with increase of molecular
weight. The higher members are odourless solids,
insoluble in water.

Formic Acid, H-COOH, when anhydrous boils at
101°. By the action of concentrated sulphuric acid,
carbon monoxide is evolved. Formic acid reduces
solutions of silver and mercury salts.

Acetic Acid, CH3-COOH, when free from water
melts at 16-5°, and boils at 118°. The addition of
ferric chloride to a neutral solution of an acetate
produces a deep red colour, which on warming dis-
appears, while a brown flocculent precipitate of basic
ferric acetate is thrown down.

When acetic acid is warmed with alcohol and con-
centrated sulphuric acid, ethyl acetate is formed,
which may be recognized by its pleasant fruity odour.

Propionic Acid, C2H5-COOH, boils at 141°. It is

ORGANIC COMPOUNDS 39

precipitated as an oil from aqueous solution by the
addition of calcium chloride. The ethyl ester boils
at 98-99°.

^Butyric Acid, CH3-CH2-CH2-COOH, boiling at
162°, has an extremely unpleasant odour. Its ethyl
ester boils at 120°.

Isobutyric Acid, ^3>CH-COOH, boils at 155°

and is insoluble in water. The ethyl ester boils at
110°.

Palmitic Acid, CH3-(CH2)14-COOH, melts at 62°.
The lead salt formed by adding lead acetate to a
neutral solution of ammonium palmitate melts at
112°.

Stearic Acid, CH3-(CH2)16-COOH, melts at 69-2°
and the lead salt at 125°.

2. SATURATED ALIPHATIC POLYBASIC ACIDS.

These acids are solids, and are soluble in water.

COOH
Oxalic Acid, | + 2H20, melts at 98°. When

COOH

acted on by concentrated sulphuric acid, carbon
monoxide and carbon dioxide are evolved. Potas-
sium permanganate reacts with oxalic acid, with for-
mation of carbon dioxide and water. The calcium
salt is insoluble in water and in acetic acid. The
dimethyl ester, which can be prepared by boiling
the anhydrous acid with methyl alcohol for about
ten minutes, is a solid melting at 54°.

40 THE IDENTIFICATION OF

POO1T
Malonic Acid, CH2, melts at 132°. On

heating more strongly, it is decomposed into acetic
acid and carbon dioxide.

CH2-COOH
Succinic Acid, | , melts at 185°. When

CH2-COOH

a neutral solution of ferric chloride is added to a
neutral solution of a succinate, a brown-red precipi-
tate of basic ferric succinate is produced. Succinic

CH2CO \
anhydride | ;Q melting at 119°, is obtained

CH2COX

by the action of acetyl chloride on the acid at 50°.
It is purified by recrystallizing from chloroform.

> melting at 97-5°,

is converted into the anhydride (M.P. 56-57°) by
heating for some time.

3. UNSATURATED ALIPHATIC ACIDS.

Acrylic Acid, CH2:CH-COOH, boils at 140° and
polymerizes. The lead salt crystallizes in fine
needles. When acrylic acid is fused with potassium
hydroxide, it is decomposed into potassium formate,
potassium acetate and hydrogen. The ethyl ester
boils at 101-102°.

Crotonic Acid, CH3-CH:CH-COOH, melting at
71-72°, when fused with potassium hydroxide pro-
duces potassium acetate and hydrogen. Its ethyl
ester boils at 142°.

ORGANIC COMPOUNDS 41

Oleie Acid, CH3-(CH2)7-CH : CH-(CH2)7-COOH,
melts at 14°, and boils at 223° at 10 mm. The lead
salt is soluble in ether and melts about 80°. When
oleic acid is shaken with nitrous acid, it is transformed
into the isomeric Elaidie Acid, melting at 44-45°.

H -C — COOH

Fumarie Acid, || , sublimes at

HOOC — C -H

200°, without melting. When distilled with phos-
phorus pentoxide, maleic anhydride (M.P. 60°) is
formed. By the action of bromine at 100° on fumaric
acid, dibromsuccinic acid, melting at 255-256° with
decomposition, is produced.

H - C - COOH

Maleic Acid, f] , melting at 130°, is

H - C - COOH

converted into the anhydride (M.P. 60°) by heating
under diminished pressure at 100°.

4. AROMATIC ACIDS.

Benzoic Acid, C6H5-COOH, melts at 121°, and can be
sublimed easily. It is practically insoluble in cold
water, easily soluble in alcohol and ether. When
heated with lime, benzene is produced. Ethyl
benzoate (B.P. 213°), a pleasant-smelling liquid, is
easily formed by heat ing together benzoic acid, ethyl
alcohol and a small quantity of concentrated sul-
phuric acid.

o-Toluie Acid, C6H4<, M.P. 102°, is easily

42 THE IDENTIFICATION OF

soluble in hot water. Dilute nitric acid oxidizes
it to phthalic acid.

m-Toluie Acid, M.P. 110°, is readily soluble in
water.

p-Toluic Acid, M.P. 176-177°. The methyl ester,
a strongly smelling solid, melts at 32°.

a-Naphthoie Acid, d0H7-COOH, M.P. 160° and

/3-Naphthoic Acid, M.P. 182° are converted into
naphthalene by distillation with lime. When the
a-compound is oxidized with chromic acid in glacial
acetic acid, phthalic acid is produced. Methyl /3-
naphthoate is a solid melting at 77°.

Phthalie Acid, C6H4<£;OOH £|, on heating forms

phthalic anhydride (M.P. 128°). When the latter
is heated with phenol and a little anhydrous zinc
chloride, phenolphthalein is produced —

2C6H5OH = H20 +

/C-C6H4OH
C6H4( /Q

\co

Phenylacetic Acid, C6H5-CH2-COOH, M.P. 76°, is
sparingly soluble in cold water.

Hydrocinnaminic Acid, C6H5-CH2-CH2-COOH, M.P.
48°.

Cinnamic Acid, C6H5-CH : CH-COOH, M.P. 133°.
The methyl ester melts at 33°.

ORGANIC COMPOUNDS 43

5. SUBSTITUTED ACIDS.

A. HYDROXY ACIDS.

Glyeollic Acid, CH2OH • COOH, melting at 78-79°,
when heated to 100° is converted into an anhydride,
M.P. 128-130°.

Lactic Acid, CH3-CHOH-COOH,is a syrup, easily
soluble in water and alcohol, difficultly soluble in
ether. Hydriodic Acid reduces it to propionic acid,
while at the same time free iodine is produced. The
silver salt melts at 100°.

CHOH-COOH
Malic Acid, , melts at 100°. When

CH2-COOH

calcium chloride and alcohol are added to a neutral
solution of a malate, calcium malate is precipitated.

CHOH-COOH
Tartaric Acid, | , melting at 168-170°,

CHOH-COOH

is decomposed on heating strongly, with production
of a smell of burnt sugar. Calcium chloride added
to a neutral solution of a tartrate (but not of tartaric
acid) precipitates calcium tartrate. When ammoni-
acal silver nitrate solution is added to a neutral
solution of a tartrate, a silver mirror is produced on
warming.

CH2-COOH

Citric Acid, C(OH)-COOH + H20, is easily soluble

CH2-COOH
in water and alcohol. It loses its water of crystalliz-

44 THE IDENTIFICATION OF

ation at 130°, and melts at 153°. When calcium
chloride is added to a neutral solution of a citrate
and the mixture heated for some time, calcium
citrate is precipitated.

Salicylic Acid, C6H4<OH melting at 155°, is

converted into phenol when it is heated with lime.
Ferric chloride added to a solution of salicylic acid
produces a deep violet colouration, which is not des-
troyed by addition of acetic acid. Methyl salicylate,
which has a characteristic odour, boils at 224°.

/OH (1)

Protocateehuie Acid, C6H34-OH (2), melts at 199*.

\COOH(4)

Ferric chloride added to a solution of the acid, pro-
duces a green colouration, which, on addition of
sodium hydroxide, changes to blue and finally to
red.

Gallic Acid, C6H2(OH)3-COOH + H20, decom-
poses at 220°, into carbon dioxide and pyrogallol
(see page 26). Ferric chloride produces a blue-
black precipitate, soluble in hydrochloric acid but
reprecipitated by ammonia.

Tannic Acid is an amorphous powder, more
soluble in water than in alcohol. Ferric chloride
solution added to a solution of the acid, produces a
blue-black colouration. When sulphuric acid is
added to a concentrated solution of tannic acid, a
white precipitate is formed, which in contact with
air turns blue.

Mandelic Acid, C6H5-CHOH-COOH, melts at 118°,

ORGANIC COMPOUNDS 45

and is easily soluble in water. Oxidation with nitric
acid produces benzaldehyde. The methyl ester
melts at 52°.

B. HALOGEN SUBSTITUTED ACIDS.

Monochloroacetie Acid, CH2C1-COOH, melting at
62-63°, heated with caustic potash forms glycollic
acid.

Dichloroacetic Acid, CHC12'COOH, is a liquid, boiling
at 189-191°.

Trichloroaeetie Acid, CC13-COOH, melts at 55°.
When digested with caustic potash, chloroform and
potassium carbonate are formed.

Monobromoacetic Acid, CH2Br-COOH, melts at
49-50°.

Dibromoaeetie Acid, CHBr2-COOH melts at 48°.

Tribromoacetie Acid, CBr3-COOH melts at 135°.

o-Chlorobenzoic Acid, C6H4, M.P. 137°.

Reduction with sodium amalgam produces benzoic
acid.

ra-Chlorobenzoie Acid, M.P. 153°.

p-Chlorobenzoie Acid, M.P. 236°.

o-Bromobenzoie Acid, C6H4<^ M.P. 147°.

ra-Bromobenzoic Acid, M.P. 155°.

p-Bromobenzoie Acid, M.P. 251°.

When the halogen benzoic acids are distilled with
lime, the corresponding halogen derivatives of
benzene are produced,

46 THE IDENTIFICATION OF

C. NITRO ACIDS.

ivro
o-Nitrobenzoie Acid, C6H^QQQH> M-

m-Nitrobenzoic Acid, M.P. 141°.
p-Nitrobenzoic Acid, M.P. 238°.

These acids can be reduced to the corresponding
amino-acids by tin and hydochloric acid.

o-Nitrocinnamic Acid, Cfl

: CH.COOHj
M.P. 237-240°.

m-Nitroeinnamie Acid, light yellow needles. M.P.
197°.

p-Nitrocinnamic Acid, M.P. 286°.

Oxidation with alkaline potassium permanganate
solution converts these acids into the corresponding
nitrobenzaldehyde and nitrobenzoic acid.

D. AMINO ACIDS.

Aminoacetic Acid (glycine), CH2NH2-COOH, M.P.
232°, with decomposition, is converted by nitrous
acid into glycollic acid. Ferric chloride added to a
solution of glycine causes an intense red colouration
which is discharged by acids, and restored by
ammonia.

Methyl Glycine (sarcosine), CH2NH(CH3)-COOH,
M.P. 210-215°, gives by the action of nitrous acid a
nitroso-compound. When heated with soda-lime,
sarcosine produces methylamine.

Aceturic Acid (Acetoglycine),

CH2NH-(COCH3)-COOH,

ORGANIC COMPOUNDS 47

melts at 206°. On boiling with acids, it is decom-
posed into glycine and acetic acid.
Hippurie Acid (Benzoylglycine),

CH2NH(COC6H5)COOH,

melting at 187°, is decomposed by boiling with
dilute acids into benzoic acid and glycine.

CH2NH-(COC6H5)-COOH +H20 = C6H5-COOH +
CH2NH2COOH.

Aminopropionie Acid (Alanine) CH3-CHNH2-COOH.
When heated with concentrated phosphoric acid
solution it is decomposed into carbon dioxide,
ammonia and acet aldehyde.

Aspartic Acid, COOH -CH2-CHNH2 -COOH. Nitrous
acid converts it into malic acid.

Asparagine, CONH2-CH2-CHNH2.COOH, forming
large rhombic crystals, decomposes over 200° with-
out melting. When heated with alkalies, ammonia
and aspartic acid are produced. With nitrous acid
it gives malic acid.

o-Aminobenzoic Acid (Anthranilic Acid),

C6H4<^ ^ melting at 144°, when rapidly

heated, decomposes into carbon dioxide and aniline.
Nitrous acid transforms it into salicylic acid.

Acetylanthranilic Acid, C6H4<°CH3, M.P.1850.

Benzoylanthranilic Acid, C6H4<65, M.P.

177°.

m-Aminobenzoie Acid forms small reddish crystals,
M,P, 173-174°,

48 THE IDENTIFICATION OF

p-Aminobenzoic Acid, M.P. 186-187°.
o-Aminocinnamic Acid, C8

CH.COOH

M.P. 158-159°, forms yellow needles and gives
fluorescent solutions in ether and alcohol.

XI. AROMATIC SULPHONIC
ACIDS.

THESE are, as a rule, very soluble in water and crystal-
lize with difficulty. To identify them, it is best to
prepare the sulphonamide and take its melting point.
The sodium salts are easily obtained by salting out.

PREPARATION OF THE AMIDE. — One gram of the
sodium salt and 2 grams phosphorus pentachloride
are heated on a water bath. After the reaction is
finished, the mixture is poured into water and the
oily acid chloride extracted by means of ether. One
gram of the oil and 2 grams of ammonium carbon-
ate are heated on a water bath until the smell of the
chloride disappears. The reaction product is then
poured into water. After filtering, the amide is
recrystallized from water and its melting-point
determined.

When a sulphonic acid or a salt is fused with alkali,
a^henol is produced —
CfiH5-S03Na +2NaOH = C6H5OH+Na2S03+H20.

METHOD.— One gram of the acid or salt is mixed

ORGANIC COMPOUNDS 49

with 2 grams solid caustic potash and heated in a
nickel crucible to about 200° for one hour. After
cooling the product is dissolved in water, the solu-
tion acidified and the phenol extracted with ether
and identified.

By passing superheated steam into the sulphonic
acid, a hydrocarbon results.

Benzene sulphonic acid, C6H5S03H, M.P. 50°.
M.P. of amide, 150°.

o-Toluene sulphonic acid, C6H4<^ 3H'2H20,
deliquescent leaflets. M.P. of amide, 155°.

m-Toluene sulphonic acid, C6H4<^O 3H -H20,
deliquescent needles. M.P. of amide, 107°.

p-Toluene Sulphonic acid, C6H43 -4H20,

crystallizes in leaflets. M.P. 92°. M.P. of amide,
137°.

o-Benzene disulphonic acid, CeH^3, M.P. of

chloride, 105° ; of amide, 233°.

m-Benzene disulphonic acid, M.P. of chloride, 53° ;
of amide, 228°.

^-Benzene disulphonic acid, M.P. of chloride, 131° ;
of amide, 288°.

o-Phenolsulphonic acid, CeH^^^-fHaO, melts

above 50°. When the potassium salt is treated
with benzoyl chloride, potassium chloride is preci-
pitated, and on extraction with ether, phenyl
benzoate is obtained,

50 THE IDENTIFICATION OF

w-Phenolsulphonic acid, CoH.i^^rr -2H20,crystal-

^bUsii

lizes in fine needles. Ferric chloride produces in
solutions of the acid, a violet colouration.

2>Phenolsulphonic Acid is oxidized by manganese
dioxide and sulphuric acid to quinone. When
boiled with hydriodic acid, £>-phenolsulphonic acid
is decomposed into phenol and sulphuric acid.

Cl
o-Chlorobenzenesulphonic acid, C6H4<^~ JT, The

chloride melts at 28-5° ; the amide at 188°.

m-Chlorobenzenesulphonie acid. The chloride is an
oil ; the amide melts at 148°.

p-Chlorobenzenesulphonic acid. M.P. of chloride,
53° ; of amide, 143°.

o-Bromobenzenesulphonic acid, C6H4<^^ ^. M.P.

of chloride, 51° ; of amide, 186°.

m-Bromobenzenesulphonie acid. The chloride is
oily. M.P. of amide, 154°.

p-Bromobenzenesulphonic acid, melts at 88°. M.P.
of chloride, 75° ; of amide, 166°.

o-Iodobenzenesulphonie acid, C6H4<^gQ g. M.P.

of chloride, 51° ; of amide, 170°.

p-Iodobenzenesulphonie acid. The chloride melts
at 86-87°; the amide at 183°.

o-Nitrobenzenesulphonic Acid, csH4<;^2H . M.P.

of chloride, 67° ; of amide, 186°.

m-Nitrobenzenesulphonic acid. M.P. of chloride,
60-5° j of amide, 161°.

ORGANIC COMPOUNDS 51

p-Nitrobenzenesulphonic acid. The chloride is oily ;
the amide melts at 181°.
p-Aminobenzenesulphonic acid (Sulphanilic acid),

C6H4<^^ \r, when oxidized gives quinone. Fusion

with caustic potash produces aniline and not amino-
phenol.

SO TT
o-Sulphobenzoie acid, <^*<C?«n> when anny-

drous melts at 250°. On fusion with caustic potash
it is converted into salicylic acid. The imino deriva-

SO
tive, C6H4<^i^'2^>NH, known as Saccharin, melts

with partial decomposition at 220°. By heating with
alkalies, saccharin is decomposed into ammonia and
o-sulphobenzoic acid. The sodium salt,

a (the saccharin of commerce) is

readily soluble in water.

a-Naphthalene sulphonic acid, C10H7S03H-H20,
M.P. 85-90°. The chloride crystallizes from ether
in leaflets, melting at 66°. The amide melts at 150°.
Potassium permanganate in acid solution oxidizes
the sulphonic acid to phthalic acid.

/3-Naphthalene sulphonic acid, M.P. 161°. The
chloride melts at 76° ; the amide at 212°.

52 THE IDENTIFICATION OF

XII. ACID ANHYDRIDES.

THE aliphatic acid anhydrides are mostly colourless
liquids, insoluble in water, readily soluble in alcohol
and ether, with boiling points higher than those of
the corresponding acids. The aromatic acid anhy-
drides are solids with melting-points lower than those
of the corresponding acids. Water slowly hydro-
lyses anhydrides with formation of acids. With
alkalies they readily form salts of the corresponding
acids, and with alcohols, esters are produced.

Acetic anhydride, (CH3CO)20, B.P. 137-138°.
CH2COV

Succinic Anhydride, | X), M.P. 119-120°,

CH2CO
reverts to the acid in moist air.

Benzoic anhydride, (C6H5CO)20, M.P. 42°.

PO
Phthalie anhydride, C6H4<^>0, melts at 128°

and sublimes readily in long needles. When fused
with resorcinol, fluorescein is produced (see p. 26).

= 2H2°

>0
C6H3OH

ORGANIC COMPOUNDS 53

XIII. ACID HALIDES.

THESE are pungent-smelling liquids, readily con-
verted by water into the acid, or by alkali into the
salt of the acid.

Acetyl chloride, CH3-COC1, B.P. 55°.

Acetyl bromide, B.P. 81°.

Acetyl iodide, B.P. 108°.

Propionyl chloride, C2H5-COC1, B.P. 80°.

Propionyl bromide, B.P. 104°.

Propionyl iodide, B.P. 127-128°.

Malonyl chloride,

CH2-COC1
Succinyl chloride, | , B.P. 190-192°.

CH2-COC1

Benzoyl chloride, C6H5-COC1, B.P. 198°.
Benzoyl bromide, B.P. 218-219°.

Phthalyl chloride, C6H4, B.P. 275°.

XIV. ACID AMIDES.

THESE are well crystallized substances with definite
melting points. They are, as a general rule, less
soluble in water than the ammonium salts of the cor-
responding acids. When heated with alkalies, they
give ammonia and the salt of the acid. With

54 THE IDENTIFICATION OF

nitrous acid they yield nitrogen and the correspond-
ing acid.

Acetamide, CH3-CONH2, M.P. 82-83°.

Propionamide, C2H5-CONH2, M.P. 79°.

Acetobromamide, CH3-CONHBr + H20, M.P. 70-
80°, when boiled with caustic potash gives potassium
bromide, carbon dioxide and methylamine. The
anhydrous compound melts at 108°.
CONH2

Oxamide, | , sublimes on heating. It is

CONH2

insoluble in water and in alcohol.

CONH2

Oxamic acid, , M.P. 210° with decompo-

COOH

sition.

CONH2
Oxamethane, , M.P. 114-115°, when

COOC2H5

boiled with caustic potash yields ammonia, ethyl
alcohol and potassium oxalate.

CH2-CONH2
Succinamide, | ,at 200° is converted into

CH2-CONH2
the imide and ammonia.

Cyanamide, CN-NH2, M.P. 40°, with copper sul-
phate gives a black compound, copper cyanamide,
CNaCu.1

Benzamide, C6H5-CONH2, M.P. 128°, is soluble in
hot water, alcohol and ether.

1 Calcium cyanamide CN2Ca is a commercial product.
On addition of water, ammonia is evolved.

ORGANIC COMPOUNDS 55

Phthalic Diamide, C6H4<2, on heating

^UUJN±12

changes to phthalimide with loss of ammonia.

XV. ACID IMIDES.

THE imides, like the acid amides, are hydrolysed by
boiling with alkalies. The only common imides are
the following : —

CH2COV
Succinimide, | >>NH, M.P. 126°.

CH2CO/

Phthalimide, C6H4<^>NH, M.P. 233-234°.

Alcoholic caustic potash precipitates the potassium

CO
salt, C6H4<^p^^>NK, from a solution of phthalimide

in alcohol. This salt is insoluble in alcohol and ether,
and sparingly soluble in water.

XVI. ACID ANTLIDES.

THESE are hydrolysed by heating with concentrated
hydrochloric acid or alkali and the aniline distilled
with steam from an alkaline solution. The acid is
then identified in the non-volatile residue.

Formanilide, H-CONHC6H5, melting at 46°, is

56 THE IDENTIFICATION OF

readily soluble in water, alcohol and ether. With
concentrated caustic soda V)lution there is produced
a crystalline sodium compound, H-CONNaC6H5.
Aeetanilide (antifebrin) CH3-CONHC6H5, M.P.lirH

COOH

Oxanilic acid, | *H20, M.P. (anhydrous)

CONHC6H5

149-150°.

CONHC6H5

Oxanilide, , M.P. 245°.

CONHC6H5

Benzanilide, C6H5-CONHC6H5, M.P. 161-162°.

XVII. ESTERS.

THESE are mostly pleasant-smelling, volatile liquids,
insoluble in water. . (Methyl oxalate and methyl
tartrate are solids.)

A small quantity of the ester is hydrolysed with
10 per cent, alkali solution, under a reflux condenser.
Two-thirds of the liquid are distilled over, de-
hydrated with potassium carbonate and examined
for the alcohol. The residue in the distilling flask
contains the alkali salt of the acid.
Formates -methyl, B.P. 32-5°.

-ethyl, B.P. 54-5°.

-propyl, B.P. 82-83°.

-butyl, B.P. 107°.

-rc-amyl, B.P. 130-5°.

ORGANIC COMPOUNDS 57

Acetates -methyl, B.P. 57-5°.

-ethyl, B.P. 77°.

-propyl, B.P. 101°.

-butyl, B.P. 125°.

-isobutyl, B.P. 116°.

-w-amyl, B.P. 148°.
Glycol monoacetate, B.P. 182°.
Glycol diacetate, B.P. 186-187°.
Glycerol triacetate, B.P. 258-259°.
Propionates-methyl, B.P. 79-5°.

-ethyl, B.P. 99°.
Butyrates-methyl, B.P. 102-3°.

-ethyl, B.P. 120°.
Oxalates-dimethyl, M.P. 54°.
-diethyl, B.P. 186°.
Malonates-dimethyl, B.P. 181-182°.

-diethyl, B.P. 198°.
Succinates-dimethyl, M.P. 18°, B.P. 195°.

-ethyl, B.P. 216°.
Malates-dimethyl, B.P. 122° at 12 mm.

-diethyl, B.P. 129° at 12 mm.

-rc-dipropyl, B.P. 150° at 12 mm.

Ethereal malates on heating under ordinary pres-
sure decompose into the corresponding fumarates.

Tartrates -dimethyl, M.P. 48°.

-diethyl, B.P. 280°.

-rc-dipropyl, B.P. 303°.
Benzoates -methyl, B.P. 199°.

-ethyl, B.P. 213°.

-n-propyl, B.P. 229°.

58 THE IDENTIFICATION OF

Glyeol di-benzoate, M.P. 73°.
Glyeerol tri-benzoate, M.P. 76°.
Salicylates -methyl, B.P. 224°.

-ethyl, B.P. 231-5°. When distilled
with barium oxide ethyl phenyl
ether is produced,
-phenyl (salol), M.P. 42-43°.
Phthalates -dimethyl, B.P. 282°.
-diethyl, B.P. 288°.
-diphenyl, M.P. 70°.

Cinnamates -methyl, M.P. 36°, B.P. 260°.
-ethyl, B.P. 271°.

phenyl, M.P. 72°. On distillation in
air, carbon dioxide and stilbene
are formed.

XVIII. QUINONES.

THESE compounds are characterized by their colour
(yellow or red), peculiar odour and volatility in
steam. With the exception of anthraquinone and
phenanthr a quinone, they are readily reduced by
sulphur dioxide to the corresponding dihydric
phenols.

Benzoquinone (quinone), C6H402, M.P. 116°, is solu-
ble in water. With phenol, quinone forms pheno-
quinone, C6H402-2C6H5OH, crystallizing in red
needles, melting at 71°. Phenoquinone is turned

ORGANIC COMPOUNDS 59

blue by caustic potash, green by barium hydroxide.
Quinone liberates iodine from potassium iodide.

o-Quinone forms bright red crystals. It has no
smell and is not volatile. It is reduced by sul-
phurous acid to catechol.

a-Naphthoquinone, C10H602, M.P. 125°, is yellow and
on oxidation with nitric acid, forms phthalic acid.

/3-Naphthoquinone decomposes about 120°. It
crystallizes in red needles. It is odourless and non-
volatile.

Anthraquinone, C14H802, M.P. 273°, when treated
with zinc dust and caustic soda, produces oxanthranol,

C6H4<C™H>C6H4, which is red. The latter

compound is easily oxidized on standing in air,
anthraquinone being again formed.

Phenanthraquinone, M.P. 205°, is not reduced by
sulphur dioxide. It dissolves in concentrated sul-
phuric acid to a dark green solution. When ignited
with zinc dust, phenanthraquinone gives phenan-
threne. The monoxime C14H80:NOH melts at
158°.

Chloranil (tetrachlorquinone), C6C1402, forms
golden-yellow leaflets, with a smell reminiscent of
Harris tweed. It sublimes undecomposed. With
caustic potash it forms the purple potassium chlor-
anilate, C6C12(OK)202. By the addition of acid to
the latter, chloranilic acid, which crystallizes in
reddish scales, is liberated.

60 THE IDENTIFICATION OF

XIX. CARBOHYDRATES.

THESE are solids, which, with the exception of starch,
are soluble in water.

d-Glucose (dextrose), C6H1206,H20, M.P. 86°.
The anhydrous compound melts at 145°. Glucose
reduces Fehling's solution. Glucosazone melts at
204-205°. Glucose pentabenzoate melts at 179°.

PREPARATION OF THE OSAZONE. — One gram of
the sugar is dissolved in 5 cc. water, and 4 grams
phenylhydrazine in 5 grams glacial acetic acid are
added. The solution is heated on a water-bath for
about ten minutes, when the osazone separates in
yellow crystals. These are dried and the melting-
point determined. This should be done quickly
as the osazone decomposes to some extent in the
neighbourhood of the melting-point.

Galactose, M.P. 163-164°. The osazone melts at
193-194°.

Fructose (laevulose), M.P. 95°. With phenyl-
hydrazine it gives c£-glucosazone. The pentaben-
zoate melts at 78-79°.

Cane Sugar, Ci2H22On, melting at 160°, does not
reduce Fehling's solution. When boiled with dilute
acids, glucose and fructose are produced. It forms
no osazone. With benzoyl chloride it gives a hexa-
benzoate, melting at 109°.

Lactose (Milk sugar), Ci2H22Oii,H20, becomes
anhydrous at 140°, and melts with decomposition

OKGANIC COMPOUNDS 61

at 205°. The osazone melts at 200°. Lactose
reduces Fehling's solution.

Maltose, C^H^Oi^HaO, loses water at 100°.
When boiled with dilute acids, glucose is formed.
The osazone melts at 190-191°.

Starch (C6H1005)n> with iodine gives a blue colour,
which disappears on heating. Starch is hydrolysed
by heating with dilute acids, forming glucose. On
boiling with water starch swells up and partially
dissolves.

XX. GLUCOSIDES.

THESE, on hydrolysis with dilute acids or alkalies,
give a sugar — generally glucose — and other sub-
stances.

Myronie Acid, C1oHi9OioNS2, usually occurs as the
potassium salt. When boiled with barium hy-
droxide it is decomposed into glucose, allyl isothio-
cyanate (see p. 92) and potassium hydrogen
sulphate.

Arbutin, C6H4<^Hll°5 |J) is soluble in water.

When ferric chloride is added to the aqueous solu-
tion, the latter is turned deep blue. On hydrolysis
with dilute sulphuric acid, glucose and hydroquin-
one are produced.

Salicin, C6H<OC6H^05 W, melting at 201°, on

62 THE IDENTIFICATION OF

hydrolysis gives glucose and saligenin. Con-
centrated sulphuric acid produces a deep red
colour. It is oxidized by chromic acid mixture to
carbon dioxide, formic acid and salicyl aldehyde.

Amygdalin, CaoH^OnN^HaO, loses water at 120°,
melting at 200° and is hydrolysed by dilute acids
into glucose, benzaldehyde and hydrocyanic acid.

Helicin, C6H4<^6^ll0s, fH20, loses water at

100° and melts at 175°. On hydrolysis with dilute
acids it gives glucose and salicyl aldehyde.

XXL AMINES.

ALIPHATIC AMINES.

THE lower members are inflammable gases possessing
an ammoniacal odour and are readily soluble in
water, while the higher members are liquids. With
acids they form salts which are soluble in water and
in alcohol.

Nitrous Acid converts primary amines into the cor-
responding alcohols, with evolution of nitrogen —

E-NH2 + HONO = R-OH + N2 + H20.

Secondary amines are converted into yellow
nitrosoamines —

R2NH + HONO = R2N-NO + H20.
Tertiary amines are unacted upon.

ORGANIC COMPOUNDS 63

METHOD. — A small quantity of the amine is dis-
solved in dilute hydrochloric acid, care being taken
that an excess of acid is present. To the cooled
solution, a solution of sodium nitrite is added until
free nitrous acid is present (starch iodine test).

Primary amines are also distinguished by giving
the carbylamine test with chloroform and alcoholic
potash —
R-NH2 + CHC13 + 3KOH = R-NC + 3KC1 + 3H20.

METHOD. — About 0-1 gram of the amine is mixed
with 3 drops chloroform and about 2 cc. alcoholic
potash solution, and gently heated. A disgusting
smell of carbylamine is evolved.

N.B. — The lower aliphatic amines are usually
met with as salts.

Methylamine Hydroehloride, CH3NH2-HC1, forms
deliquescent crystals.

Ethylamine, C2H5NH2, B.P. 18-19°. The hydro-
chloride melts at 76-80°.

Diethylamine, (C2H5)2NH, B.P. 56°. M.P. of hydro-
chloride 215-217°.

Triethylamine, (C2H5)3N, B.P. 89°.

Propylamine, (C3H7)NH2, B.P. 49°. The
chloride melts at 157-158°.

Isopropylamine, (CH3)2CHNH2, B.P. 31-32°. The
hydrochloride is deliquescent.

7i-Butylamine, C4H9NH2, B.P. 76°.

rc-Amylamine, CgHnNKU B.P. 103°.

Allylamine, CH2 : CH-CH2NH2. B.P. 56°.

Ethylenediamine, C2H4(NH2)2, B.P. 116°. Nitrous
acid converts it into ethylene oxide.

64 THE IDENTIFICATION OF

Tetramethylenediamine (putrescine), C4H8(NH2)2,
M.P. 27-28°.

Pentamethylene Diamine (cadaverine), C5H10(NH2)2.
B.P. 178-179°.

AROMATIC AMINES.

These are liquids or solids, and behave in many
respects like the aliphatic amines. The primary
compounds give the carbylamine reaction.

ACTION OF NITKOUS ACID. — If the amino group is
in the nucleus there are formed in cold acid solution
diazonium salts, which on heating evolve nitrogen
and produce phenols. If to a solution of a diazonium
salt /9-naphthol in caustic soda is added, a coloured
precipitate of an azo-compound appears.

PREPARATION OF A DIAZONIUM SALT. — The amine
is dissolved in a large excess of dilute hydrochloric
acid and cooled in ice-water. Sodium nitrite solu-
tion is added in small quantities at a time, the mix-
ture being well shaken after each addition, until,
after standing for a few minutes, free nitrous acid
can be detected by starch-iodide paper.

If the amino group is in the side chain, no diazon-
ium salt is formed, and the amine behaves like the
aliphatic compounds.

With secondary aromatic amines, nitroso-deriva-
tives are formed, as in the case of aliphatic com-
pounds.

Dialkylanilines with nitrous acid form para-
nitroso compounds, the free bases of which are
usually green, while the hydrochlorides are orange-
coloured.

ORGANIC COMPOUNDS 65

To completely identify an aromatic amine, its
acetyl compound is prepared and its melting-point
determined.

METHOD. — To 1 gram of the amine is added 1 gram
acetic anhydride. The solid acetyl compound
usually separates immediately. It is recrystallized
from water or alcohol and its melting-point taken.

Aniline, C6H5NH2, B.P. 182-183°. A chip of
pine wood dipped first in hydrochloric acid and then
in aniline, is turned yellow. Bleaching powder
solution, when shaken with aniline becomes violet.
On diazotizing and warming, aniline is converted
into phenol. Acetanilide melts at 112°.

Methylaniline, C6H5NHCH3, B.P. 193-194°, forms
a nitroso-derivative, C6H5NCH3-NO, M.P. 12-15°.
The acetyl derivative melts at 101-102°.

Dimethylaniline, C6H5N(CH3)2, boils at 195°. The
para-nitroso compound, which can be separated from
its salts by means of sodium carbonate and extrac-
tion with ether, forms green crystals of metallic
appearance, melting at 85°.

Ethylaniline, C6H5NHC2H6, B.P. 206°. The acetyl
derivative melts at 54*5°.

Diethylaniline, C6H5N(C2H6)2, B.P. 213-214°.
p-Nitroso-compound M.P. 84°.

Diphenylamine, (C6H5)2NH, melts at 54° and has a
pleasant odour. The nitroso-derivative melts at
66-5°.

Triphenylamine, (C6H5)3N, M.P. 127°. With con-
centrated sulphuric acid, there is produced a violet
colouration, which changes to green.

66 THE IDENTIFICATION OF

pro

o-Toluidine, C6H4<^3 , boils at 197°. Ferric

chloride precipitates a blue compound from its solu-
tion in hydrochloric acid. The acetyl compound
melts at 110°.

ra-Toluidine, B.P. 202°. The acetyl compound
melts at 65°.

p-Toluidine, M.P. 45°. The melting point of the
acetyl compound is 153°.

a-Naphthylamine, C10H7NH2, M.P. 50°. On oxida-
tion with chromic acid, a-naphthaquinone is pro-
duced.

/3-Naphthylamine, M.P. 111-112°. Potassium per-
manganate oxidizes it to phthalic acid.

Benzylamine, C6H5-CH2NH2, B.P. 183-185° is
strongly alkaline.

o-Phenylenediamine,C6H4<^2,M.P. 102°. When

ferric chloride is added to the hydrochloric acid
solution, a dark red colouration is produced, and
there quickly separate red needles of diamido-

phenazine C6H4<^>C6H2 (NH2)2. The di-acetyl

compound of o-phenylenediamine melts at 185-186°.
m-Phenylenediamine, M.P. 63°. Dilute nitrous acid
produces a brown colouration owing to the formation
NH2

M" ,NH2
i i
N • N — I

NH3

OEGANIC COMPOUNDS 67

p-Phenylenediamine, M.P. 147°. When about 0-1
gram is dissolved in dilute hydrochloric acid and a
little sulphuretted hydrogen water added along with
a few drops of ferric chloride solution, and the mix-
ture warmed, there appears a deep violet colouration
(the so-called Lauth violet),

HN = / \ =N -

Benzidine, NH2C6H4-C6H4NH2 melting at 122°,
forms silvery leaflets, easily soluble in hot water and
alcohol. The sulphate is insoluble in water.

HALOGEN AMINES.

pi
o-Chloroaniline, C6H4<^H , B.P. 207°. The

acetyl compound melts at 87-88°.

m-Chloroaniline, B.P. 230°. M.P. of acetyl com-
pound, 72-5°.

p-Chloroaniline, M.P. 70°. M.P. of acetyl com-
pound, 172-5°.

o-Bromoaniline, GsH4<^g , M.P. 31°. M.P. of

acetyl compound, 99°.

ra-Bromoaniline, M.P. 18°, B.P. 251°. M.P. of
acetyl compound, 87' 5°.

23-Bromoaniline, M.P. 63°. M.P. of acetyl com-
pound, 167-168°.

68 THE IDENTIFICATION OF

Cl
Sym. Trichloroaniline, NH2/ \ Cl, M.P.

Cl
77-5°. M.P. of acetyl compound, 204°.

Sym. Tribromoaniline, M.P. 119-120°. M.P. of
acetyl compound, 232°.

XXII. NITRO-COMPOUNDS.

ALIPHATIC NITRO-COMPOUNDS.

THESE are agreeably-smelling liquids, soluble in
water. Many of them dissolve in alkalies.

ACTION OF NITROUS ACID. — With a primary ali-
phatic nitro-compound nitrous acid produces a red
colouration due to the formation of a nitrolic acid.

K-CH2N02 + HONO= R-C< +H20.

The potassium salt is red.

With a secondary compound there is produced a
dark blue colouration, a pseudo-nitrol being formed —
R2CHN02 + HONO = !^C<2 + H20.

Tertiary compounds are unacted upon by nitrous
acid.

METHOD. — A small quantity of the compound is
shaken in a test-tube with sufficient caustic soda to
form a clear solution. A few drops of a solution of
sodium nitrite are added and finally dilute sulphuric

ORGANIC COMPOUNDS 69

acid drop by drop. In the case of a primary com-
pound excess of acid destroys the red colouration,
which, however, is restored by addition of caustic
soda.

REDUCTION. — Nitro-compounds are readily re-
duced to amines.

METHOD. — A few pieces of granulated zinc are
placed on a test-tube and covered with caustic potash
solution. Two cc. of the nitro-compound are intro-
duced and the mixture warmed. The amine will
be observed by its smell and its action on red litmus
paper.

Nitromethane, CH3N02, B.P. 101°. Alcoholic
caustic soda precipitates the sodium compound,
CH2:NO2Na. Concentrated hydrochloric acid de-
composes it with formation of formic acid.

Nitroethane, C2H5N02, B.P. 114-115°. Concen-
trated hydrochloric acid converts it into acetic acid.

Nitropropane, C3H7N02, B.P. 130-131°.

Tertiary Nitrobutane, (CH3)3-CN02, is crystalline,
melting at 24°. It is insoluble in alkalies.

AROMATIC NITRO-COMPOUNDS.

These are generally yellow oils or solids, insoluble
in water, dilute hydrochloric acid or dilute caustic
soda solution. Di-nitro and tri-nitro compounds
impart a deep yellow colour to caustic soda solution .

They are reduced to amines by acid reducing
agents.

METHOD. — A small quantity of the nitro-compound

70 THE IDENTIFICATION OF

is treated with zinc dust and hydrochloric acid, heat
being applied if necessary. The mixture is diluted
and rendered alkaline with caustic soda. It is then
extracted with ether and the amine identified.

Nitrobenzene, C6H5N02, B.P. 209°, is a yellow oil
with an odour of bitter almonds. On reduction it
yields aniline.

o-Nitrotoluene, C6H4<^3, boils at 218°. It gives

o-toluidine on reduction.

ra-Nitrotoluene, melts at 16°, and boils at 230-231°.
p-Nitrotoluene, M.P. 54°.

o-Dinitrobenzene, C6H4<^°2, M.P. 117-118°. On

reduction it gives o-phenylenediamine.

m-Dinitrobenzene, M.P. 91°.

p-Dinitrobenzene, M.P. 171-172°.

a-Nitronaphthalene, Ci0H7N02, melting at 61°, on
reduction yields a-naphthylamine and with chromic
acid is oxidized to nitrophthalic acid.

/3-Nitronaphthalene, M.P. 79°, gives on reduction
/3-naphthylamine .

NITROPHENOLS.

These compounds, on reduction with tin and
hydrochloric acid, yield aminophenols.

o-Nitrophenol, C6H4<^2, melting at 44°, has an
intense yellow colour and a peculiar odour. It is

OKGANIC COMPOUNDS 71

easily volatile in steam. The sodium salt gives a
red solution in water.

ra-Nitrophenol, M.P. 96°, forms sulphur-yellow
crystals.

p-Nitrophenol, M.P. 114°, forms colourless needles
which turn pink on exposure to air. The potassium
salt is yellow. Phosphorus pentachloride converts
the phenol into p-chloronitrobenzene, M.P. 83°.
OH

N°2'M.P. 122-123° forms

NO 2

yellow leaflets soluble in hot water. With aromatic
hydrocarbons crystalline molecular compounds are
obtained (see Naphthalene, p. 17). When picric
acid is warmed with a concentrated solution of potas-
sium cyanide, a dark red solution of isopurpuric acid
is produced.

NITROKETONES.

o-Nitroaeetophenone, C6H4N02CO-CH3, is an oil with
a peculiar smell. It is oxidized by potassium per-
manganate to o-nitrobenzoic acid.

m-Nitroacetophenone forms needles melting at 80-
81°. The oxime melts at 131°.

23-Nitroacetophenone, crystallizes in yellow prisms,
melting at 80-81°.

NITROANILINES.

These are solids, yellow or orange in colour. They

72 THE IDENTIFICATION OF

have basic properties and are soluble in acids. On
reduction with tin and hydrochloric acid the
corresponding diamines are produced.

o-Nitroaniline,C6H4<^jj2, crystallizes in orange-
yellow needles, melting at 71°. When boiled
with alkali it loses ammonia with production of
o-nitrophenol. The acetyl derivative melts at 92°.

m-Nitroaniline, melting at 114°, forms yellow
needles and is not acted on by alkali. The acetyl
compound melts at 150°.

p-Nitroaniline, M.P. 147°, is decomposed by boiling
alkali solution into ammonia and ^-nitrophenol.
The acetyl compound melts at 207°.
NH2

Picramide, 2 , forms orange-red

N02

needles melting at 188°. When heated with alkali,
alkali picrate is formed, and ammonia is evolved.

XXIII. NITROSO-COMPOUNDS.

Nitrosobenzene, C6H5NO, M.P. 68°, when fused or
in solution has an intense greenish-blue colour.

^-Nitrosoaniline, C6H4<^Tr > forms steel-blue

ORGANIC COMPOUNDS 73

needles, melting at 174°. On boiling with caustic
soda, it forms ammonia and p-nitrosophenol.

p-Nitrosophenol, C§H«<, M.P. 126°, is slightly

soluble in water, giving a light green solution. It
is reduced by tin and hydrochloric acid to p-amino-
phenol. Concentrated nitric acid oxidizes it to
£>-nitrophenol.

Methyl-p-nitrosoaniline, C<nrnt / forms

large crystals with metallic lustre, M.P. 118°. When
boiled with caustic soda solution, it is decomposed
into nitrosophenol and methylamine.

°6H<NHCH3 +H2° = C6
p-Nitrosodimethylaniline, C6H4<^;TT x , forms

green crystals, melting at 85°. The hydrochloride is
yellow and is soluble with difficulty in water. Dilute
caustic soda solution on warming decomposes the
base into ^-nitrosophenol and dimethylamine. It
does not give Liebermann's nitroso reaction.

a-Nitrosonaphthol (a-naphthoquinone oxime),
Ci0H6(OH)(NO) 1 : 4, forms needles melting with
decomposition at 193-194°.

/3-Nitrosonaphthol (/3-naphthoquinone oxime),
C10H6(OH)(NO) 1 : 2, crystallizes in yellowish-green
needles, melting with decomposition at 152°. It
dissolves in concentrated sulphuric acid with an
intense red colour. When a neutral solution of the

74 THE IDENTIFICATION OF

sodium salt of /3-nitroso-naphthol is added to a cobalt
salt solution, a brown-red precipitate is formed.

XXIV. NITRILES AND ISONI-
TRILES.

THE nitriles are liquids or solids of low melting-point,
and have an agreeable odour. When boiled with
strong mineral acids they are hydrolysed into the
corresponding acids —

CH3-CN + 2H20 = CHs'COOH + NH3
With nascent hydrogen they are reduced to amines.
CHs-CN + 4H=CH3-CH2NH2.

HYDROLYSIS OF NITRILES. — Two cc. of the sub-
stance are boiled for some time with about 20 cc.
concentrated hydrochloric acid. The liquid is then
rendered alkaline with caustic soda and heated.

The residual liquid is tested for the fatty acid.

REDUCTION OF NITRILES. — One cc. of the sub-
stance is treated with 10 cc. dilute hydrochloric acid
and a little zinc dust. The solution is rendered
alkaline with caustic soda, and the amine identified.

Acetonitrile, CH3'CN. is a colourless liquid, boiling
at 81-82°.

Benzonitrile, C6H5-CN, B.P. 191°, is an oil with the
odour of bitter almonds.

Isonitriles or Carbylamines are not usually met with
unless in testing for primary amines. They are

ORGANIC COMPOUND (, 75

liquids possessing a disgusting odour. On hydro-
lysis with acids they yield formic acid and an
amine.

R-N^C + 2H20=R-NH2 +H-COOH.

XXV. ISOCYANATES.

THESE are liquids, which, when digested with caustic
potash yield primary amines and potassium carbon-
ate, and with acids, a salt of a primary amine and
carbon dioxide —

R-N:C:0 +H20 =RN-H2 +C02.

Methyl Isocyanate, B.P. 44°.
Ethyl Isocyanate, B.P. 60°.
Allyl Isocyanate, B.P. 82°.
Phenyl Isocyanate, B.P. 165-166°.

XXVI. UREAS AND UREIDES.

WHEN ureas and alkyl ureas are digested with caustic
soda solution sodium carbonate remains, while
from the former ammonia is evolved, from the latter
amines. In the case of ureides, ammonia or amines
may be given off, and the residue consists of sodium
carbonate and the sodium salt of the acid of the
ureide.

76 THE IDENTIFICATION OF

CO^2 + 2NaOH = Na2C03 +2NH3.
-\JN-ti2

+ 2NaOH=Na2C03+CH3.NH2+NH3

CO— NH COONa

| >CO + 4NaOH = Na2C03 + +

CO— NH COONa

2NH3

Urea, CONH2, M.P. 132-133°, is a colourless solid;

When treated with nitrous acid it is decomposed
into nitrogen and carbon dioxide —

CO(NH2)2 + 2HONO = C02 + 2N2 + 3H20.
With a solution of sodium hypobromite it gives the
same decomposition products —
CO(NH2)2 + 3NaBrO =C02 + 3NaBr+N2+ 2H20.

BIURET REACTION. — When urea is heated above its
melting-point, ammonia is evolved and a residue of
biuret remains —

2CO(NH2)2 = NH3 + NH2-CO-NH-CO-NH2.

When the biuret is dissolved in water and copper
sulphate added and then caustic potash drop by
drop, a violet colouration appears.

Methylurea, CO , crystallizes in prisms,

melting at 102°. On heating for some time it decom-
poses into ammonia, methylamine and the dimethyl
ester of cyanuric acid, which melts at 222°.

ORGANIC COMPOUNDS 77

Ethylurea, CO , melts at 92°. It decom-

poses on heating, into ammonia, ethylamine and
the diethyl ester of cyanuric acid, M.P. 173°.

CO— NH

Parabanic Acid (Oxalylurea), | ^>CO, on

CO— NH

heating with caustic potash solution gives potassium
oxalate, potassium carbonate and ammonia.

Barbituric Acid (Malonylurea ) , CO ^>CH 2 , on

heating with caustic potash solution yields potassium
malonate, potassium carbonate and ammonia.

Alloxan(Mesoxalylurea),CO ^>CO, has an

acid reaction. Ferrous sulphate gives a deep blue
colour to the solution. When alloxan is boiled with
dilute nitric acid, it is decomposed into parabanic
acid and carbon dioxide.

Guanidine, CNH, is a deliquescent strongly

basic substance. The nitrate, M.P. 214°, dissolves
with difficulty in water. When boiled with alkalies,
guanidine is decomposed giving ammonia and alkali
carbonate.

78 THE IDENTIFICATION OF

XXVII. URIC ACID GROUP.

NH -CO
C-

Uric Acid, CO C-NH

| || CO, is insoluble in

NH - C-

alcohol, and practically insoluble in water.

1. When the acid is heated with soda lime
ammonia is evolved.

2. MUREXIDE TEST. — A small quantity of the acid
is moistened with concentrated nitric acid, and the
mixture evaporated to dryness in a porcelain basin
on a water-bath. There remains a reddish residue,
which on addition of dilute ammonia solution
changes to purple red, while alkali produces a violet
colouration.

3. Fehling's solution is reduced by uric acid.

4. If a little of the acid be dissolved in a drop of
caustic soda solution and this placed on filter paper
which has been moistened with a solution of silver
nitrate, a dark brown spot of metallic silver is
immediately produced.

5. On dry distillation, uric acid decomposes
without melting, giving off ammonia and hydro-
cyanic acid,

ORGANIC COMPOUNDS 79

NH-CO

Xanthine, CO C — NHV is a colourless

I II >CH

NH -C N/^

powder, soluble with difficulty in water, but very
easily soluble in alkalies.

When a small quantity of xanthine is warmed with
freshly-made chlorine water and a trace of nitric
acid until evolution of gas ceases, the solution
then carefully evaporated to dryness, and the solid
exposed to ammonia gas, a rose-red colour is pro-
duced.

If xanthine be evaporated with nitric acid (Sp.
Gr. 1 -4), the residue is yellow. On addition of caustic
potash it becomes yellowish red, and on warming
violet-red.

CH3N - CO

Caffeine, CO C - NCH3 M.P. 226-229°,

I li \CH ,
CH3N - C-N/"

is fairly soluble in water and in alcohol.

When evaporated with concentrated nitric acid
it gives the murexide test (see Uric Acid).

When caffeine is evaporated with chlorine water,
it leaves a purple red residue, which on strongly
heating becomes yellow, but on addition of ammonia
is changed to red.

80 THE IDENTIFICATION OF

XXVIII. HALOGEN COMPOUNDS.

ALIPHATIC.

THE alkyl halides are liquids which have a high
specific gravity, and are practically insoluble in
water. They are hydrolysed to the corresponding
alcohols by warming with an excess of alkali
solution.

Ethyl bromide, C2H5Br, B.P. 39°.

Ti-Propyl bromide, C3H7Br, B.P. 71°.

Isopropyl bromide, CH3-CHBr.CH3, B.P. 59-60°.

Methyl iodide, B.P. 43°.

Ethyl iodide, B.P. 72°.

Propyl iodide, B.P. 102°.

Isopropyl iodide, B.P. 89-5°.

Allyl chloride, CH2 : CH-CH2C1, B.P. 46°, has a
leek-like odour.

Allyl bromide, B.P. 70-71°.

Allyl iodide, B.P. 102-103°.

Methylene iodide, CH2I2, boils at 180° with partial
decomposition.

Ethylene chloride, CH2C1-CH2C1, B.P. 84°.

Ethylene bromide, B.P. 131-132°.

Ethylene iodide, melts at 81-82°.

Chloroform, CHC13, B.P. 61 -5°, is a colourless
non-inflammable liquid. When boiled with alco-
holic caustic potash, potassium formate and potas-
sium chloride are formed —

OHC13 + 4KOH = H-COOK + 3KC1 + 2H30,

ORGANIC COMPOUNDS 81

The carbylamine test may also be applied (see
page 11).

Bromoform, CHBr3, B.P. 151°.

lodoform, CHI3, M.P. 119-120°, crystallizes in
brilliant yellow leaflets of a characteristic odour.

Carbon tetrachloride, CC14, B.P. 76-77°, is a pleasant
smelling liquid. When treated with zinc and
hydrochloric acid, it is reduced to chloroform.
On heating with alcoholic potash it is decomposed
into potassium carbonate and potassium chloride.

CC14 + 6KOH = K2C03 + 4KC1 + 3H20.

AROMATIC HALOGEN COMPOUNDS

are divided into two classes : —

1. True aromatic halogen compounds, i.e. those
with the halogen attached to the benzene nucleus.

2. Those with the halogen in the side chain.
The members of the first class are colourless

liquids or solids, with a faint, agreeable odour.
They are insoluble in water, but readily soluble
in the other common solvents. They easily form
nitro-derivatives. Caustic alkali does not readily
remove the halogen from these compounds.

Monochlorobenzene, C6H5C1, B.P. 132°.

o-Dichlorobenzene, C6H4C12, B.P. 179°.

ra-Dichlorobenzene, B.P. 172°.

p-Diehlorobenzene, M.P. 53°.

Monobromobenzene, C6H5Br,$B.P. 156-157°.

o-Dibromobenzene, C6H4Br2, B.P. 224°.

w-Dibromobenzene, B.P. 219°.

82 THE IDENTIFICATION OF

p-Dibromobenzene, M.P. 89°.
lodobenzene, C6H5I, B.P. 188°.

o-Chlorotoluene, CeH^™3 , B.P. 156°.

ra-Chlorotoluene, B.P. 150°.
p-Chlorotoluene, B.P. 163°.

o-Bromotoluene, C6H4<^3 , B.P. 181°.

ra-Bromotoluene, B.P. 183-184°.
p-Bromotoluene, M.P. 28-29°.
a-Chloronaphthalene, C10H7C1, B.P. 263°.
/3-Chloronaphthalene, M.P. 56°, B.P. 265°.

The compounds with halogen in the side chain
behave like aliphatic halogen compounds.

Benzyl chloride, C6H5-CH2C1, B.P. 175°, when
boiled with a solution of copper nitrate, benzaldehyde
is formed —

2C6H5-CH2C1 +Cu(N03)2 = 2C6H5-CHO + CuCl2 +
2HN02.

Benzal chloride (benzylidene chloride ), C6H5-CHC12,
B.P. 206°, forms benzaldehyde, when heated with
milk of lime —

C6H5.CHCl2+Ca(OH)2=C6H5.CHO+CaCl2+H20.

Benzotrichloride, C6H5-CC13, B.P. 2 13°, on heating
with milk of lime, gives calcium benzoate —

2C6H5.CC13 +4Ca(OH)2 = (C6H5-COO)2Ca +
3CaCl2 + 4H20.

ORGANIC COMPOUNDS 83

XXIX. AZO COMPOUNDS.

THESE compounds are coloured solids, which on
reduction produce amino compounds.

C6H5N:NC6H5 + 4H = C6H5NH2 + C6H5NH2.

azobenzene

p-amidoazobenzene p-phenylenediamine

C6H5N:NC6H4OH+4H = C6H5NH2+C6H4NH2OH

p-oxyazobenzene p-aminophenol

S03HC6H4N : NC6H4N(CH3)2 + 4H =

Helianthine

S03HC6H4NH2 + NH2C6H4N(CH3)2

Sulphanilic acid p-amido-dimethylaniline

METHOD OF REDUCTION. — About 3 grams of the
compound are warmed with zinc dust and water
until the colour has disappeared. The mixture is
then extracted with ether and the ethereal solution
evaporated to dryness. The residue may be : —

1. A mixture of two amines.

2. A mixture of an amine and an aminophenol.

3. A mixture of an amine and an aminosulphonic
acid.

MIXTURE OF Two AMINES. — The residue of liquid
is distilled and the first and last fractions treated
with acetic anhydride. The acetyl compounds
thus formed are then identified by their melting
points.

MIXTURE OF AN AMINE AND AN AMINOPHENOL. —
The aminophenol is extracted from the mixture with
alkali.

84 THE IDENTIFICATION OF

MIXTURE OF AN AMINE AND AN AMINOSTJLPHONIC
ACID. — The mixture is neutralized with alkali, the
amine extracted with ether, and identified. The
aminosulphonic acid is liberated by adding hydro-
chloric acid to the alkali salt.

Azobenzene, C6H5N : NC6H5, M.P. 68°, is easily
soluble in alcohol. When treated with tin and
hydrochloric acid, benzidine is produced.

p-Aminoazobenzene, C6H5N : NC6H4NH2, forms
yellow leaflets melting at 125-126°. It is oxidized
by sulphuric acid and manganese dioxide with
formation of quinone. The hydrochloride crystal-
lizes in steel-blue needles. The acetyl derivative
melts at 142°.

Diaminoazobenzene, C6H5N :

forms yellow needles, M.P. 117°. On reduction it
yields aniline and triaminobenzene, M.P. 132°.
The hydrochloride of diaminoazobenzene is known
as ehrysoidine.

Triaminoazobenzene, NH2C6H,N:NC6H3<^2,(^,

JN±l2(4:)

M.P. 143°.

Helianthine, S03HC6H4N : NC6H4N(CH3)2, forms
glistening violet leaflets. On reduction it yields
sulphanilic acid and p-amino-dimethylaniline, M.P.
41°. The sodium salt is known as Methyl Orange.

The following, which are related to the azo-
compounds, should also be mentioned.

Hydrazobenzene, C6H5NH -NHC6H5, M.P. 131°,
forms colourless leaflets, which are insoluble in water.

ORGANIC COMPOUNDS 85

If its alcoholic solution be exposed to air, azo-
benzene is produced. Powerful reducing agents
decompose it into aniline.

Azoxybenzene, C6H5N — NC6H5, crystallizes in long

\/
0

yellow needles, M.P. 36°. It is insoluble in water.
On distillation it decomposes into azobenzene and
aniline.

Diazoaminobenzene, C6H5N : N-NHC6H5, melts at
96° and explodes at higher temperatures.

XXX. PYRIDINE AND
QUINOLINE GROUP.

Pyridine, C5H5N, B.P. 116°, has a strong char-
acteristic odour, and is miscible in all proportions
with water, alcohol and ether. It forms salts with
acids. On reduction with sodium and alcohol,
piperidine is produced.

Piperidine, CsH^N, B.P. 106°, is a colourless liquid
with a characteristic odour. It is miscible with
water, alcohol and ether. It is a secondary amine.

Quinoline, C9H7N, B.P. 239°, is sparingly soluble
in water. The hydrochloride is crystalline. With
methyl iodide quinoline forms a yellow crystalline
compound melting at 72°.

86 THE IDENTIFICATION OF

XXXI. ALKALOIDS.

THE alkaloids are nearly all solids, easily soluble in
alcohol, soluble with difficulty in ether, chloroform
and benzene, and sparingly soluble or insoluble in
water. Most are optically active, generally laevo-
rotatory. They dissolve readily in dilute acids
with formation of salts, from which the alkaloid is
precipitated on addition of an alkali. Morphine,
however, is soluble in excess of sodium hydroxide.
The following reactions are given by almost all
the alkaloids : —

1. When an alkaloid is heated in a dry test-tube,
decomposition takes place with production of a
smell like burning feathers.

2. A solution of iodine in potassium iodide pro-
duces a brown flocculent precipitate in solutions
of salts of the alkaloids, best when acidified with
dilute sulphuric acid.

3. Phosphomolybdic acid l produces a yellow
precipitate in solutions of all the alkaloids. The
precipitate is soluble in alkalies and alkaline car-
bonates.

4. Potassium mercuric iodide 2 produces a white
or yellowish white precipitate in solutions of salts
of alkaloids. The precipitates are insoluble in
dilute hydrochloric acid.

5. Aqueous solutions of tannic acid and of picric
acid precipitate all or nearly all the alkaloids from
solutions of their salts.

1 See Appendix. 2 See Appendix.

ORGANIC COMPOUNDS 87

CH3

CH N

HC C HC CJ

Nicotine, || | is a colour-

HC CH H2C CH2,

\ y

less oil with an unpleasant smell, B.P. 247°.

Picric acid produces an amorphous precipitate
which readily crystallizes in small yellow needles
melting at 218°.

Quinine, when anhydrous melts at 177°. The
normal salts are sparingly soluble, the acid salts
very soluble.

Solutions of quinine salts, when acidified with
sulphuric acid show a fine blue fluorescence.

Concentrated sulphuric acid dissolves the alkaloid
to a colourless solution, which on heating turns
brown and yellow.

When a solution of a quinine salt is mixed with
one-fifth of its volume of chlorine water and then
with an excess of ammonia, an emerald green
colour is produced. If a little potassium ferro-
cyanide solution be added after the chlorine water
and then a few drops of ammonia, the solution
becomes deep red in colour.

Cinehonine, M.P. 250°.

When chlorine water and an excess of ammonia
are added to a solution of a cinchonine salt, a
yellowish white precipitate is formed.

88 THE IDENTIFICATION OF

When potassium ferrocyanide is added to a
neutral or slightly acid solution of a cinchonine
salt, a yellowish white flocculent precipitate is
produced.

When chlorine water is added drop by drop to a
solution of a brucine salt, there is produced a red
colouration which is destroyed by excess of chlorine.

Strychnine, M.P. 284°.

If a crystal of potassium dichromate be stirred
in a solution of the alkaloid in concentrated sul-
phuric acid, there appears a fine blue colour, which
changes successively to violet, red and reddish
yellow.

Potassium ferricyanide and also potassium chro-
mate produce yellow crystalline precipitates in
neutral and fairly concentrated solutions of strych-
nine salts.

Brucine, when anhydrous melts at 178°.

The solution in concentrated sulphuric acid has
at first a rose-red colour, which changes to yellow.

Concentrated nitric acid dissolves brucine and
its salts giving an intensely red solution, which,
when warmed, turns yellow. If stannous chloride
be added to this yellow solution, an intense violet
colouration is produced.

Morphine is soluble in dilute acids and in alkalies.
Its salts dissolve easily in water and alcohol.

The addition of concentrated nitric acid to the
solid alkaloid or a salt causes a yellowish red colour
to appear.

When ammonium molybdate in concentrated

ORGANIC COMPOUNDS 89

sulphuric acid (0-1 gram in a cc.) is placed in a
porcelain dish and a particle of morphine added
and crushed with a glass rod, a deep violet colour
appears, which slowly changes to blue.

If a few drops of a dilute neutral solution of
ferric chloride be added to a concentrated solution
of a morphine salt, a dark blue colouration is
produced. The colour is destroyed by acids.

Narcotine, M.P. 176°.

Cold concentrated sulphuric acid dissolves the
alkaloid, giving a yellow solution. If this be care-
fully heated in a porcelain dish, the colour changes
from yellow through orange to red, while a bluish
violet colour appears at the edges. If the heating
be continued until the acid begins to evaporate,
the solution acquires a reddish violet colour.

If to a solution of narcotine in concentrated
sulphuric acid there be added 10 to 20 drops sul-
phuric acid containing a trace of nitric acid, the
liquid turns brown and then quickly red.

XXXII. SULPHUR COMPOUNDS.

(OTHER THAN SULPHONIC ACIDS AND
DERIVATIVES.)

Carbon Bisulphide, CS2, is a highly refractive colour-
less liquid boiling at 47°. When it is added to
alcoholic potash, potassium xanthate is precipitated
in yellow needles —

90 THE IDENTIFICATION OP

^OC2H5
CS2 + KOH + C2H5OH = CS + H20.

MERCAPTANS OR THIO-ALCOHOLS.

These are colourless liquids with a disagreeable
garlic-like odour, and are insoluble in water.

1. Oxidation with nitric acid produces sulphonic
acids which can be identified by conversion into their
amides (see page 48).

2. When a mercaptan is added to a few cc. of an
alcoholic solution of mercuric chloride, a white
precipitate is formed.

3. When sodium is added to a mercaptan in
ethereal solution, hydrogen is evolved and the
sodium salt crystallizes in white needles.

Ethyl mercaptan, C2H5SH, B.P. 36°.
rc-Propyl mercaptan, C3H7SH, B.P. 68°.
Isopropyl mercaptan, (CH3)2CHSH, B.P. 59°.

THIOETHERS OR ALKYL SULPHIDES.

The thioethers are colourless liquids with a
disagreeable odour, insoluble in water, but easily
soluble in alcohol and ether. They are characterized
by their additive powers ; for example, they unite
with alkyl iodides to form sulphine iodides.

One cc. ethyl iodide is added to 1 cc. of the
thioether and the mixture warmed. After adding
about a gram of moist silver oxide, the mixture is

'•

ORGANIC COMPOUNDS 91

shaken with water, again warmed and filtered.
The filtrate will be strongly alkaline owing to the
presence of trialkyl sulphoxide.

R2g + C2H5I =R2EtSI

R2EtSI + AgOH = R2EtS-OH + Agl.

Methyl sulphide, (CH3)2S3 B.P. 37-5°.

Ethyl sulphide, (C2H5)2S, B.P. 92°.

n-Propyl Sulphide, (C3H7)2S, B.P. 130-135°.

Allyl Sulphide, (CH3-CH : CH)2S, B.P. 139-140°,
forms a crystalline precipitate with alcoholic
mercuric chloride.

Thiophene, C4H4S, B.P. 84°.

When a crystal of isatin is dissolved in 2 cc.
cone, sulphuric acid, and to this solution a few
drops of thiophene are added, a deep blue colour is
produced.

COMPOUNDS CONTAINING NITROGEN AND
SULPHUR.

MUSTARD OILS OR ISOTHIOCYANATES.

These are liquids with a very penetrating odour.
They are insoluble in water. Their boiling points
are lower than those of the corresponding thio-
cyanates.

1. When heated to 100° with concentrated
hydrochloric acid under a reflux condenser, they
are decomposed into amines, sulphuretted hydrogen
and carbon dioxide —

R-NCS +2H20 =R-NH2 +C02 +H2S.

92 THE IDENTIFICATION OF

2. Reduction by means of zinc and hydrochloric
acid produces an amine and thiof ormaldehyde, which
has an odour of onions —

R-NCS + 2H2 = R-NH2 + H-CHS.

3. One cc. of the mustard oil is warmed with one
cc. aniline for a few minutes. On cooling, a
thiourea crystallizes out, and its melting point is
determined (see p. 93).

+ C6H5NH2 = CS

4. If 1 cc. of the mustard oil be heated with one
gram yellow mercuric oxide, an isocyanate and a
black precipitate of mercuric sulphide are formed.

Methyl mustard oil, CSNCH3, M.P. 35°.

Ethyl mustard oil, CSNC2H5, B.P. 131-132°.

Allyl mustard oil, CSNC3H5, B.P. 150-7°.

Phenyl mustard oil, CSNC6H5, B.P. 222°, when
reduced with zinc dust gives benzonitrile.

THIOUREAS.

When a thiourea is heated with concentrated
hydrochloric acid under a reflux condenser for
some time and then distilled, the distillate contains
a mustard oil. If the residue, which contains a
guanidine derivative, be heated with concentrated
caustic soda solution, an amine and a carbonate
are produced.

(a) CS =RNCS+R-NH3

ORGANIC COMPOUNDS 93

(6) CS +RNH2 = C = NR + H2S

XKTHR

Thiourea, CS , M.P. 172°, when boiled with

alkalies, hydrochloric acid or sulphuric acid, is
decomposed.

CS + 2H20 = C02 + 2NH3 + H2S.
\NH2

^NHCH3

Methylthiourea, CS , M.P. 118°.

^NH2

^NHCH3

Dimethylthiourea, CS , M.P. 51-5°.

^NHCH3

^•NHC2H5

Ethylthiourea, CS , M.P. 113°.

\NH2

^-NHC2H5

Diethylthiourea, CS , M.P. 77°.

\NHC2H5

^NHCH2CH:CH2

Allylthiourea, CS , M.P. 78-5

^-NH2

^NHC6H5
Phenylthiourea, CS , M.P. 154°.

94 THE IDENTIFICATION OF

^NHC6H6

/Stym-Diphenylthiourea, CS , M.P. 151

\NHC6H5

^NHC6H5
Phenylmethylthiourea, CS , M.P. 113°.

\NHCH3
^NHC6H5
Phenylethylthiourea, CS , M.P. 99-5°.

THIOCYANATES.

1. When a thiocyanate is reduced with zinc dust
and hydrochloric acid, a mercaptan and hydrocyanic
acid 1 are produced —

CNSR + H2 = CNH + R-SH.

2. Boiling nitric acid oxidizes thiocyanates to
alkyl sulphonic acids.

Methyl thiocyanate, CNSCH3, B.P. 133°.
Ethyl thioeyanate, CNSC2H5, B.P. 142°.
Allyl thiocyanate, CNSC3H5, B.P. 161°, rapidly
changes on boiling to the isomeric mustard oil.

XXXIII. TERPENES AND
ALLIED COMPOUNDS.

THESE compounds, although possessing many of
the properties of compounds already considered,
have distinctive characteristics, thus necessitating

1 Since hydrocyanic acid is a poison, great care must be
taken in carrying out this reaction.

OEGANIC COMPOUNDS 95

their separate classification. They are neither
aliphatic nor aromatic, and are complex in structure.
Nevertheless, they yield characteristic derivatives
which as a general rule can be easily identified. They
are all highly inflammable, possess characteristic
odours and are insoluble in water, but are readily
soluble in most organic solvents.

HYDROCARBONS.

Dipentene, C10H16, B.P. 175-176°. The dihydro-
Moride, Ci0H16'2HCl, is prepared by passing dry
hydrochloric acid over a few cc. dipentene for
about one hour. The dihydrochloride separates on
pouring the mixture on ice. It is dried on a
porous plate and recrystallized from alcohol. M.P.
48-50°.

Dipentene tetrabromide, Ci0H16Br4, can be made
by adding bromine to a chloroform solution of
dipentene, cooled to -10° by salt and ice. The
chloroform is removed by blowing a current of dry
air through the solution. The tetrabromide on
recrystallization from ethyl acetate, melts at 125°.

The active forms of dipentene are the limonenes.
The active tetrabromides melt at 104°.

Pinene, C10H16, B.P. 155-156°.

The nitrosochloride, C10H16NOC1, melts at 115°.
It is prepared by adding 1-5 cc. 33 per cent, hydro-
chloric acid to a mixture (cooled in ice) of 5 grams
pinene, 5 grams glacial acetic acid, and 5 grams
ethyl nitrite. After a short time the nitrosochloride

96 THE IDENTIFICATION OF

separates in large crystals. It is filtered off at the
pump and washed with alcohol.

Camphene, C10H16, melts at 51°.

When heated with glacial acetic acid and a little
sulphuric acid, camphene forms isobornyl acetate.
On adding water the ester separates as an oil. It
is hydrolysed with alcoholic caustic potash, the
alcohol removed, and isoborneol is precipitated on
addition of water. Isoborneol melts about 208° in
a closed tube.

Menthene, C10H18, B.P. 167-168°. The nitroso-
chloride melts at 127°.

ALCOHOLS.

Terpineol, d0H17OH, melts at 35°. It forms a
nitrosochloride melting at 112-113°.

Borneol, C10H17OH, M.P. 203-204°, and Iso-
borneol, C10H17OH, M.P. 208°, yield derivatives of
very similar melting and boiling points. The
phenylurethanes of both melt at 138-139°.

PREPARATION OF APHENYLURETHANE. — Molecular
quantities of the alcohol and phenyl isocyanate 1
are mixed and heated rapidly to boiling. The mix-
ture is well shaken and allowed to stand, the flask
being closed with a calcium chloride tube. The
unchanged phenyl isocyanate is extracted with
benzene, and the residual urethane, after removal
of benzene, is washed with cold water and re-
crystallized from ethyl acetate or a mixture of

1 This preparation should be carried out in a draught-
cupboard.

ORGANIC COMPOUNDS 97

ether and petroleum ether. (Solvents containing
"hydroxyl" should be avoided.)

When isoborneol is heated for some time with
ethyl alcohol and concentrated sulphuric acid, iso-
bornyl ethyl ether (B.P. 203-204°) is produced.
Bornyl ethyl ether is not formed in this way.

Menthol, C10H19OH, M.P. 42°. The phenyl-
urethane forms needles, melting at 111°.

KETONES.

Carvone, C10H140, B.P. 223-224°. On heating
with a little acid it is converted into carvacrol.

Camphor, C10H160, M.P. 177-178°. The oxime
melts at 120° ; the semicarbazone at 236°.

Menthone, C10H180, B.P. 208°, has a peppermint-
like odour. The semicarbazone melts at 184°.

XXXIV. ALBUMINS AND
PROTEIDS.

THESE are compounds of very complicated structure,
and, with a few exceptions, do not crystallize. They
are insoluble in the common organic solvents, but
dissolve in aqueous solutions of acids and alkalies.
The following are general tests for the albumins : —
I. MILLON'S KB AGENT (a solution of mercuric
nitrate containing nitrous acid) gives an intense red
colouration on heating.

II. XANTHO-PROTEIN REACTION. — By heating
an albumin with fairly concentrated nitric acid,
there separates a yellow flocculent precipitate
of xanthoproteic acid, which dissolves in alkali
giving an orange red solution.

III. BIURET REACTION. — When caustic potash is
added to albumin, and then a very dilute solution
of copper sulphate drop by drop, a fine violet-
red colouration appears.

Egg-albumin is soluble in water and is precipitated
from its solutions by metaphosphoric acid and by
acetic acid. The precipitate is soluble in excess
of the latter. Egg-albumin treated with con-
centrated sulphuric acid and sugar solution gives
a red solution which changes to violet-red.

Casein contains phosphorus. An alkaline solu-
tion of casein dissolves cupric hydrate, giving a
violet colour.

Gelatine contains sulphur. It is precipitated
from its solutions by tannin.

Appendix.

MELTING-POINT APPARATUS. — The^ sketch shows an
apparatus which is very convenient "and gives very

3-3 cms.

Il-Scms.

4 cms.

4-8cms

accurate determinations.

SPECIAL REAGENTS.

NEUTRAL FERRIC CHLORIDE SOLUTION. — To some of
the ferric chloride solution provided in the laboratory r
dilute ammonium hydroxide or ammonium carbonate
is added drop by drop until a precipitate just begins to*
form.

SCHIFF'S REAGENT. — Sulphurous acid is added to a
dilute solution of rosaniline hydrochloride (magenta)
until the colour just disappears.

100 APPENDIX

FEHLING'S SOLUTION. — (I) 35 grams copper sulphate
are dissolved in water and diluted to 1 litre. (2) 173
grams sodium potassium tartrate (Rochelle salt) and 70
.grams caustic soda are dissolved in water and diluted
to 1 litre.

These solutions are kept in separate bottles. Equal
volumes of each are mixed immediately before making
a test.

SOLUTION OF IODINE IN POTASSIUM IODIDE. — 5 grams
of iodine are dissolved in water containing 10 grams of
potassium iodide and the solution made up to 1 litre.
HYDRIODIC ACID. — To obtain the constant boiling
solution (Sp. Gr. 1-7) hydriodic acid of Sp. Gr. 2-00 is
diluted with an equal volume of water and distilled over
a small quantity of red phosphorus. The fraction
boiling at 125°-126° is collected separately.

SODIUM BISULPHITE (saturated solution). — Sulphur
dioxide is passed into a saturated solution of sodium
carbonate for some time. Solid carbonate is added,
from time to time, until no more dissolves. The final
solution should smell strongly of sulphur dioxide.

PHOSPHOMOLYBDIC ACID. — To a solution of 75 grams
ammonium molybdate in 500 cc. nitric acid (Sp. Gr. 1-2)
,and 500 cc. water, sodium phosphate solution is added
until there is no further precipitate. This is then filtered
off, well washed and finally warmed with sodium car-
bonate solution until completely dissolved. The solu-
tion is evaporated to dryness, and the residue ignited.
The product is warmed with water and dissolved in
a considerable excess of nitric acid.

POTASSIUM MERCURIC IODIDE. — 13 grams mercuric
chloride and 50 grams potassium iodide are dissolved hi
water and the mixture made up to 1 litre.

MILLON'S REAGENT. — A small quantity of mercury is
dissolved in twice its weight of concentrated nitric acid
in the cold and twice its volume of water is added.

INDEX

Acetyl compounds of
amines, preparation of

Acid amides ....

Acid anhydrides.

Acid anilides

Acid halides ....

Acid imides ....

Acids, aliphatic mono-
basic saturated

Acids, aliphatic poly-
basic saturated .

Acids, aliphatic unsatu-
rated

Acids, amino.

Acids, aromatic .

Acids, aromatic sulphonic

Acids, halogen substi-
tuted

Acids, hydroxy .

Acids, nitro ....

Albumins

Alcohol phenols .

Alcohols, polyhydric

Alcohols, primary mono-
hydric

Alcohols, secondary mono-
hydric

Alcohols, tertiary mono-
hydric

Aldehyde ethers

Aldehyde group, detec-
tion of .

PAGE pAGEr

Aldehydes .... 29

Aldehydes substituted . 33

Alkaloids 8$

Alkyl sulphides ... 90

Amines, aliphatic . . 62

Amines, aromatic . . 64

Amines, halogen . 67
Amino group, detection

of 11

Aminophenols ... 29

Azo compounds ... 83

Azo group, detection of 14

Biuret reaction ... 76-

Carbohydrates ... 60
Chromic acid oxidation

mixture 15>

Diazonium salt, prepara-
tion of 64

65
53
52
55
53
55

38
39

40
46
41

45
43
46
97
27
21

19
21

21
36

Esters 56

Ethers 22

Ethoxy group, detection

of * 9

101

102

INDEX

PAGE

Fehling's solution, pre-
paration of ...
Ferric chloride, neutral
solution

G.
Glucosides ....

99
99

Melting-point apparatus
Mendius' reaction . 13
Mercaptans ....
Methoxy group, detec-
tion of
Millon's reagent, prepara-
tion of
Mustard oils ....

N.
Nitriles . . «

99
,74

100
91

Halogen compounds, ali-

Nitriles, detection of .

Halogen compounds, aro-
matic
Halogen phenols.
Hydriodic acid, constant

100

Nitro compounds, ali-
phatic
Nitro compounds, aro-
matic
Nitro group, detection of

69
3

Hydrocarbons, aliphatic
Hydrocarbons, aromatic
Hydroxyl group, detec-
tion of

Tmino group, detection of
Iodine in potassium io-

14
15

100

Nitroanilines ....
Nitro-ketones
Nitrophenols ....
Nitroso compounds .
Nitrosochloride, prepara-
tion of a .

Oxidation with chromic

71
71

95
18

Isocyanates ....
Isonitriles
Jsonitriles, detection of .
Jsothiocyanates .

Ketone group, detection
of

75
74
13
91

Oximes, preparation of

P.
Phenols
Phenols, alcohol .
Phenols, halogen
Phenylhydrazones, pre-
paration of ...

27
27

.Ketones . . .

Phenylurethanes, pre-

Ketones, nitro- .

Liebermann's test .

71
12

paration of ...
Phosphomolybdic acid,
preparation of ' .
Picrates, preparation of
Piperidine ....

100
17

INDEX

103

PAGE

Potassium mercuric io-
dide, preparation of . 100

Proteids 97

Pyridine 85

Quinoline 85

Quinones 58

Schiffs reaction ... 10

Schiff's reagent, prepara-
tion of 99

Schotten-Baumann reac-
tion 8

Semicarbazones, prepar-
ation of .... 30

Sodium bisulphite, pre-
paration of . . . 100

SuJphonamides, prepara-
tion of . 48

PAGE

Sulphur compounds. . 89

Terpenes 94

Tests for elements . . 4

Tests, preliminary . . 1

Thioalcohols .... 90

Thiocyanates . ... 94

Thio-ethers .... 90

Thiophene .... 91

Thioureas 92

Tollen's reaction . 9

Ureas 75

Ureides 75

Unsaturation, tests for 4

Uric acid group ... 78

Butler & Tanner. 'The Selwood Printing Works, Frome, anc

TfnRNTA

14 DAY USE

«N TO DESK FROM WHICH BORROWED

LOAN DEPT.

Berkeley

YB 16724

UNIVERSITY OF CALIFORNIA LIBRARY

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